[JAVA][NATIVE] Add gzip capability (#22358)

* add gzip capability

* fixed test

* added docstring

* regenerated samples

modules/openapi-generator/src/main/resources/Java/libraries/native/ApiClient.mustache

@@ -11,6 +11,10 @@ import org.openapitools.jackson.nullable.JsonNullableModule;
 {{/openApiNullable}}
 
 import java.io.InputStream;
+import java.io.IOException;
+{{#useGzipFeature}}
+import java.io.ByteArrayOutputStream;
+{{/useGzipFeature}}
 import java.net.URI;
 import java.net.URLEncoder;
 import java.net.http.HttpClient;
@@ -25,6 +29,13 @@ import java.util.Collections;
 import java.util.List;
 import java.util.StringJoiner;
 import java.util.function.Consumer;
+import java.util.Optional;
+import java.util.zip.GZIPInputStream;
+{{#useGzipFeature}}
+import java.util.function.Supplier;
+import java.util.Objects;
+import java.util.zip.GZIPOutputStream;
+{{/useGzipFeature}}
 import java.util.stream.Collectors;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -54,7 +65,7 @@ public class ApiClient {
   protected String basePath;
   protected Consumer<HttpRequest.Builder> interceptor;
   protected Consumer<HttpResponse<InputStream>> responseInterceptor;
-  protected Consumer<HttpResponse<String>> asyncResponseInterceptor;
+  protected Consumer<HttpResponse<InputStream>> asyncResponseInterceptor;
   protected Duration readTimeout;
   protected Duration connectTimeout;
 
@@ -378,7 +389,7 @@ public class ApiClient {
    *                    of null resets the interceptor to a no-op.
    * @return This object.
    */
-  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<String>> interceptor) {
+  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<InputStream>> interceptor) {
     this.asyncResponseInterceptor = interceptor;
     return this;
   }
@@ -388,7 +399,7 @@ public class ApiClient {
    *
    * @return The custom interceptor that was set, or null if there isn't any.
    */
-  public Consumer<HttpResponse<String>> getAsyncResponseInterceptor() {
+  public Consumer<HttpResponse<InputStream>> getAsyncResponseInterceptor() {
     return asyncResponseInterceptor;
   }
 
@@ -448,4 +459,142 @@ public class ApiClient {
   public Duration getConnectTimeout() {
     return connectTimeout;
   }
+
+  /**
+   * Returns the response body InputStream, transparently decoding gzip-compressed
+   * payloads when the server sets {@code Content-Encoding: gzip}.
+   *
+   * @param response HTTP response whose body should be consumed
+   * @return Original or decompressed InputStream for the response body
+   * @throws IOException if the response body cannot be accessed or wrapping fails
+   */
+  public static InputStream getResponseBody(HttpResponse<InputStream> response) throws IOException {
+    if (response == null) {
+      return null;
+    }
+    InputStream body = response.body();
+    if (body == null) {
+      return null;
+    }
+    Optional<String> encoding = response.headers().firstValue("Content-Encoding");
+    if (encoding.isPresent()) {
+      for (String token : encoding.get().split(",")) {
+        if ("gzip".equalsIgnoreCase(token.trim())) {
+          return new GZIPInputStream(body);
+        }
+      }
+    }
+    return body;
+  }
+
+{{#useGzipFeature}}
+  /**
+   * Wraps a request body supplier with a streaming GZIP compressor so large payloads
+   * can be sent without buffering the entire contents in memory.
+   *
+   * @param bodySupplier Supplies the original request body InputStream
+   * @return BodyPublisher that emits gzip-compressed bytes from the supplied stream
+   */
+  public static HttpRequest.BodyPublisher gzipRequestBody(Supplier<InputStream> bodySupplier) {
+    Objects.requireNonNull(bodySupplier, "bodySupplier must not be null");
+    return HttpRequest.BodyPublishers.ofInputStream(() -> new GzipCompressingInputStream(bodySupplier));
+  }
+
+  private static final class GzipCompressingInputStream extends InputStream {
+    private final Supplier<InputStream> supplier;
+    private final byte[] readBuffer = new byte[8192];
+    private final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+    private InputStream source;
+    private GZIPOutputStream gzipStream;
+    private byte[] currentChunk = new byte[0];
+    private int chunkPosition = 0;
+    private boolean finished = false;
+
+    private GzipCompressingInputStream(Supplier<InputStream> supplier) {
+      this.supplier = Objects.requireNonNull(supplier, "bodySupplier must not be null");
+    }
+
+    private void ensureInitialized() throws IOException {
+      if (source == null) {
+        source = Objects.requireNonNull(supplier.get(), "bodySupplier returned null InputStream");
+        gzipStream = new GZIPOutputStream(buffer, true);
+      }
+    }
+
+    private boolean fillBuffer() throws IOException {
+      ensureInitialized();
+      while (chunkPosition >= currentChunk.length) {
+        buffer.reset();
+        if (finished) {
+          return false;
+        }
+        int bytesRead = source.read(readBuffer);
+        if (bytesRead == -1) {
+          gzipStream.finish();
+          gzipStream.close();
+          source.close();
+          finished = true;
+        } else {
+          gzipStream.write(readBuffer, 0, bytesRead);
+          gzipStream.flush();
+        }
+        currentChunk = buffer.toByteArray();
+        chunkPosition = 0;
+        if (currentChunk.length == 0 && !finished) {
+          continue;
+        }
+        if (currentChunk.length == 0 && finished) {
+          return false;
+        }
+        return true;
+      }
+      return true;
+    }
+
+    @Override
+    public int read() throws IOException {
+      if (!fillBuffer()) {
+        return -1;
+      }
+      return currentChunk[chunkPosition++] & 0xFF;
+    }
+
+    @Override
+    public int read(byte[] b, int off, int len) throws IOException {
+      if (!fillBuffer()) {
+        return -1;
+      }
+      int bytesToCopy = Math.min(len, currentChunk.length - chunkPosition);
+      System.arraycopy(currentChunk, chunkPosition, b, off, bytesToCopy);
+      chunkPosition += bytesToCopy;
+      return bytesToCopy;
+    }
+
+    @Override
+    public void close() throws IOException {
+      IOException exception = null;
+      if (source != null) {
+        try {
+          source.close();
+        } catch (IOException e) {
+          exception = e;
+        } finally {
+          source = null;
+        }
+      }
+      if (gzipStream != null) {
+        try {
+          gzipStream.close();
+        } catch (IOException e) {
+          exception = exception == null ? e : exception;
+        } finally {
+          gzipStream = null;
+        }
+      }
+      if (exception != null) {
+        throw exception;
+      }
+    }
+  }
+{{/useGzipFeature}}
 }

modules/openapi-generator/src/main/resources/Java/libraries/native/api.mustache

@@ -49,6 +49,9 @@ import java.util.Map;
 import java.util.Set;
 import java.util.Locale;
 import java.util.function.Consumer;
+{{#useGzipFeature}}
+import java.util.function.Supplier;
+{{/useGzipFeature}}
 {{#asyncNative}}
 
 import java.util.concurrent.CompletableFuture;
@@ -84,7 +87,7 @@ public class {{classname}} {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public {{classname}}() {
     this(Configuration.getDefaultApiClient());
@@ -102,15 +105,33 @@ public class {{classname}} {
 
   {{#asyncNative}}
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
   {{/asyncNative}}
   {{^asyncNative}}
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -130,10 +151,13 @@ public class {{classname}} {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -349,27 +373,8 @@ public class {{classname}} {
     {{/asyncNative}}
     {{#asyncNative}}
     try {
-      HttpRequest.Builder localVarRequestBuilder = {{operationId}}RequestBuilder({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("{{operationId}}", localVarResponse));
-            }
-            {{#returnType}}
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<{{{returnType}}}>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-            {{/returnType}}
-            {{^returnType}}
-            return CompletableFuture.completedFuture(null);
-            {{/returnType}}
-      });
+      return {{operationId}}WithHttpInfo({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -430,6 +435,7 @@ public class {{classname}} {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("{{operationId}}", localVarResponse);
@@ -438,7 +444,8 @@ public class {{classname}} {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -460,7 +467,8 @@ public class {{classname}} {
         {{! A fix for that problem is to read it into a string and remove those characters, but if we need to read it before giving it to jackson to fix the string then just reading it into a string as is to do an emptiness check is the cleaner solution. }}
         {{! We could also manipulate the inputstream to remove that bad character, but string manipulation is easier to read and this codepath is not asyncronus so we do not gain anything by reading the stream later. }}
         {{! This fix does make it unsuitable for large amounts of data because `InputStream.readAllbytes` is not meant for it, but a synchronous client is already not the right tool for that.}}
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<{{{returnType}}}>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -469,17 +477,16 @@ public class {{classname}} {
         }
 
         {{^isResponseFile}}{{#isResponseBinary}}
-        Byte[] responseValue = localVarResponse.body().readAllBytes();
+        Byte[] responseValue = localVarResponseBody.readAllBytes();
         {{/isResponseBinary}}{{/isResponseFile}}
         {{#isResponseFile}}
         // Handle file downloading.
-        File responseValue = downloadFileFromResponse(localVarResponse);
+        File responseValue = downloadFileFromResponse(localVarResponse, localVarResponseBody);
         {{/isResponseFile}}
         {{^isResponseBinary}}{{^isResponseFile}}
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         {{{returnType}}} responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<{{{returnType}}}>() {});
         {{/isResponseFile}}{{/isResponseBinary}}
-        localVarResponse.body().close();
 
         return new ApiResponse<{{{returnType}}}>(
             localVarResponse.statusCode(),
@@ -488,6 +495,10 @@ public class {{classname}} {
         );
         {{/returnType}}
         {{^returnType}}
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<{{{returnType}}}>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
@@ -496,13 +507,9 @@ public class {{classname}} {
         {{/returnType}}
         {{/vendorExtensions.x-java-text-plain-string}}
       } finally {
-        {{^returnType}}
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
-        {{/returnType}}
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -517,31 +524,78 @@ public class {{classname}} {
       HttpRequest.Builder localVarRequestBuilder = {{operationId}}RequestBuilder({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}}{{#hasParams}}, {{/hasParams}}headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("{{operationId}}", localVarResponse));
             }
-            {{#returnType}}
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<{{{returnType}}}>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<{{{returnType}}}>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                {{#vendorExtensions.x-java-text-plain-string}}
+                if (localVarResponse.headers().map().containsKey("Content-Type") &&
+                        "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
+                  java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
+                  String responseBodyText = s.hasNext() ? s.next() : "";
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<String>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          responseBodyText
+                      )
+                  );
+                } else {
+                  return CompletableFuture.failedFuture(new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse));
+                }
+                {{/vendorExtensions.x-java-text-plain-string}}
+                {{^vendorExtensions.x-java-text-plain-string}}
+                {{#returnType}}
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<{{{returnType}}}>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                {{^isResponseFile}}{{#isResponseBinary}}
+                Byte[] responseValue = localVarResponseBody.readAllBytes();
+                {{/isResponseBinary}}{{/isResponseFile}}
+                {{#isResponseFile}}
+                File responseValue = downloadFileFromResponse(localVarResponse, localVarResponseBody);
+                {{/isResponseFile}}
+                {{^isResponseBinary}}{{^isResponseFile}}
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                {{{returnType}}} responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<{{{returnType}}}>() {});
+                {{/isResponseFile}}{{/isResponseBinary}}
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<{{{returnType}}}>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+                {{/returnType}}
+                {{^returnType}}
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+                {{/returnType}}
+                {{/vendorExtensions.x-java-text-plain-string}}
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
-            {{/returnType}}
-            {{^returnType}}
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
-            {{/returnType}}
         }
       );
     }
@@ -644,15 +698,32 @@ public class {{classname}} {
     localVarRequestBuilder.header("Content-Type", "{{#hasConsumes}}{{#consumes}}{{#-first}}{{{mediaType}}}{{/-first}}{{/consumes}}{{/hasConsumes}}{{#hasConsumes}}{{^consumes}}application/json{{/consumes}}{{/hasConsumes}}{{^hasConsumes}}application/json{{/hasConsumes}}");
     {{/bodyParam}}
     localVarRequestBuilder.header("Accept", "{{#hasProduces}}{{#produces}}{{{mediaType}}}{{^-last}}, {{/-last}}{{/produces}}{{/hasProduces}}{{#hasProduces}}{{^produces}}application/json{{/produces}}{{/hasProduces}}{{^hasProduces}}application/json{{/hasProduces}}");
+    {{#useGzipFeature}}
+    localVarRequestBuilder.header("Accept-Encoding", "gzip");
+    {{/useGzipFeature}}
 
     {{#bodyParam}}
     {{#isString}}
+    {{#useGzipFeature}}
+    Supplier<InputStream> localVarRequestBodySupplier = () -> new ByteArrayInputStream({{paramName}}.getBytes(java.nio.charset.StandardCharsets.UTF_8));
+    localVarRequestBuilder.header("Content-Encoding", "gzip");
+    localVarRequestBuilder.method("{{httpMethod}}", ApiClient.gzipRequestBody(localVarRequestBodySupplier));
+    {{/useGzipFeature}}
+    {{^useGzipFeature}}
     localVarRequestBuilder.method("{{httpMethod}}", HttpRequest.BodyPublishers.ofString({{paramName}}));
+    {{/useGzipFeature}}
     {{/isString}}
     {{^isString}}
     try {
       byte[] localVarPostBody = memberVarObjectMapper.writeValueAsBytes({{paramName}});
+      {{#useGzipFeature}}
+      Supplier<InputStream> localVarRequestBodySupplier = () -> new ByteArrayInputStream(localVarPostBody);
+      localVarRequestBuilder.header("Content-Encoding", "gzip");
+      localVarRequestBuilder.method("{{httpMethod}}", ApiClient.gzipRequestBody(localVarRequestBodySupplier));
+      {{/useGzipFeature}}
+      {{^useGzipFeature}}
       localVarRequestBuilder.method("{{httpMethod}}", HttpRequest.BodyPublishers.ofByteArray(localVarPostBody));
+      {{/useGzipFeature}}
     } catch (IOException e) {
       throw new ApiException(e);
     }
@@ -690,6 +761,39 @@ public class {{classname}} {
     {{/isArray}}
     {{/formParams}}
     HttpEntity entity = multiPartBuilder.build();
+    {{#useGzipFeature}}
+    Supplier<InputStream> formDataSupplier;
+    if (hasFiles) {
+        Pipe pipe;
+        try {
+            pipe = Pipe.open();
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        new Thread(() -> {
+            try (OutputStream outputStream = Channels.newOutputStream(pipe.sink())) {
+                entity.writeTo(outputStream);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }).start();
+        formDataSupplier = () -> Channels.newInputStream(pipe.source());
+    } else {
+        ByteArrayOutputStream formOutputStream = new ByteArrayOutputStream();
+        try {
+            entity.writeTo(formOutputStream);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        byte[] formBytes = formOutputStream.toByteArray();
+        formDataSupplier = () -> new ByteArrayInputStream(formBytes);
+    }
+    localVarRequestBuilder
+        .header("Content-Type", entity.getContentType().getValue())
+        .header("Content-Encoding", "gzip")
+        .method("{{httpMethod}}", ApiClient.gzipRequestBody(formDataSupplier));
+    {{/useGzipFeature}}
+    {{^useGzipFeature}}
     HttpRequest.BodyPublisher formDataPublisher;
     if (hasFiles) {
         Pipe pipe;
@@ -713,12 +817,14 @@ public class {{classname}} {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("{{httpMethod}}", formDataPublisher);
+    {{/useGzipFeature}}
     {{/isMultipart}}
     {{^isMultipart}}
     List<NameValuePair> formValues = new ArrayList<>();
@@ -743,10 +849,20 @@ public class {{classname}} {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
+    {{#useGzipFeature}}
+    Supplier<InputStream> formDataSupplier = () -> new ByteArrayInputStream(formBytes);
+    localVarRequestBuilder
+        .header("Content-Type", entity.getContentType().getValue())
+        .header("Content-Encoding", "gzip")
+        .method("{{httpMethod}}", ApiClient.gzipRequestBody(formDataSupplier));
+    {{/useGzipFeature}}
+    {{^useGzipFeature}}
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("{{httpMethod}}", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
+    {{/useGzipFeature}}
     {{/isMultipart}}
     {{/hasFormParams}}
     {{^hasFormParams}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java

@@ -3533,8 +3533,9 @@ public class JavaClientCodegenTest {
         assertNotNull(apiFile);
 
         JavaFileAssert.assertThat(apiFile).fileContains(
-                //reading the body into a string, then checking if it is blank.
-                "String responseBody = new String(localVarResponse.body().readAllBytes());",
+                // reading the body into a string after decompression, then checking if it is blank.
+                "localVarResponseBody = ApiClient.getResponseBody(localVarResponse);",
+                "String responseBody = new String(localVarResponseBody.readAllBytes());",
                 "responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<LocationData>() {})"
         );
     }
@@ -3627,9 +3628,10 @@ public class JavaClientCodegenTest {
         File apiFile = files.get("DefaultApi.java");
         assertNotNull(apiFile);
 
-        JavaFileAssert.assertThat(apiFile).fileDoesNotContain(
-                //reading the body into a string, then checking if it is blank.
-                "String responseBody = new String(localVarResponse.body().readAllBytes());",
+        JavaFileAssert.assertThat(apiFile).fileContains(
+                // async path should also decompress before reading the body.
+                "InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);",
+                "String responseBody = new String(localVarResponseBody.readAllBytes());",
                 "responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<LocationData>() {})"
         );
     }

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/ApiClient.java

@@ -20,6 +20,7 @@ import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import org.openapitools.jackson.nullable.JsonNullableModule;
 
 import java.io.InputStream;
+import java.io.IOException;
 import java.net.URI;
 import java.net.URLEncoder;
 import java.net.http.HttpClient;
@@ -34,6 +35,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.StringJoiner;
 import java.util.function.Consumer;
+import java.util.Optional;
+import java.util.zip.GZIPInputStream;
 import java.util.stream.Collectors;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -62,7 +65,7 @@ public class ApiClient {
   protected String basePath;
   protected Consumer<HttpRequest.Builder> interceptor;
   protected Consumer<HttpResponse<InputStream>> responseInterceptor;
-  protected Consumer<HttpResponse<String>> asyncResponseInterceptor;
+  protected Consumer<HttpResponse<InputStream>> asyncResponseInterceptor;
   protected Duration readTimeout;
   protected Duration connectTimeout;
 
@@ -384,7 +387,7 @@ public class ApiClient {
    *                    of null resets the interceptor to a no-op.
    * @return This object.
    */
-  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<String>> interceptor) {
+  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<InputStream>> interceptor) {
     this.asyncResponseInterceptor = interceptor;
     return this;
   }
@@ -394,7 +397,7 @@ public class ApiClient {
    *
    * @return The custom interceptor that was set, or null if there isn't any.
    */
-  public Consumer<HttpResponse<String>> getAsyncResponseInterceptor() {
+  public Consumer<HttpResponse<InputStream>> getAsyncResponseInterceptor() {
     return asyncResponseInterceptor;
   }
 
@@ -454,4 +457,32 @@ public class ApiClient {
   public Duration getConnectTimeout() {
     return connectTimeout;
   }
+
+  /**
+   * Returns the response body InputStream, transparently decoding gzip-compressed
+   * payloads when the server sets {@code Content-Encoding: gzip}.
+   *
+   * @param response HTTP response whose body should be consumed
+   * @return Original or decompressed InputStream for the response body
+   * @throws IOException if the response body cannot be accessed or wrapping fails
+   */
+  public static InputStream getResponseBody(HttpResponse<InputStream> response) throws IOException {
+    if (response == null) {
+      return null;
+    }
+    InputStream body = response.body();
+    if (body == null) {
+      return null;
+    }
+    Optional<String> encoding = response.headers().firstValue("Content-Encoding");
+    if (encoding.isPresent()) {
+      for (String token : encoding.get().split(",")) {
+        if ("gzip".equalsIgnoreCase(token.trim())) {
+          return new GZIPInputStream(body);
+        }
+      }
+    }
+    return body;
+  }
+
 }

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/api/AuthApi.java

@@ -73,7 +73,7 @@ public class AuthApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public AuthApi() {
     this(Configuration.getDefaultApiClient());
@@ -91,7 +91,15 @@ public class AuthApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -110,10 +118,13 @@ public class AuthApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -199,6 +210,7 @@ public class AuthApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testAuthHttpBasic", localVarResponse);
@@ -206,7 +218,8 @@ public class AuthApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -217,6 +230,9 @@ public class AuthApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -297,6 +313,7 @@ public class AuthApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testAuthHttpBearer", localVarResponse);
@@ -304,7 +321,8 @@ public class AuthApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -315,6 +333,9 @@ public class AuthApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/api/BodyApi.java

@@ -83,7 +83,7 @@ public class BodyApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public BodyApi() {
     this(Configuration.getDefaultApiClient());
@@ -101,7 +101,15 @@ public class BodyApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -120,10 +128,13 @@ public class BodyApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -209,11 +220,13 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testBinaryGif", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<File>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -223,9 +236,8 @@ public class BodyApi {
 
         
         // Handle file downloading.
-        File responseValue = downloadFileFromResponse(localVarResponse);
+        File responseValue = downloadFileFromResponse(localVarResponse, localVarResponseBody);
         
-        localVarResponse.body().close();
 
         return new ApiResponse<File>(
             localVarResponse.statusCode(),
@@ -233,6 +245,9 @@ public class BodyApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -317,6 +332,7 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testBodyApplicationOctetstreamBinary", localVarResponse);
@@ -324,7 +340,8 @@ public class BodyApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -335,6 +352,9 @@ public class BodyApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -425,6 +445,7 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testBodyMultipartFormdataArrayOfBinary", localVarResponse);
@@ -432,7 +453,8 @@ public class BodyApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -443,6 +465,9 @@ public class BodyApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -497,8 +522,9 @@ public class BodyApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
@@ -566,6 +592,7 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testBodyMultipartFormdataSingleBinary", localVarResponse);
@@ -573,7 +600,8 @@ public class BodyApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -584,6 +612,9 @@ public class BodyApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -632,8 +663,9 @@ public class BodyApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
@@ -701,11 +733,13 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEchoBodyAllOfPet", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Pet>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -715,10 +749,9 @@ public class BodyApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Pet>(
             localVarResponse.statusCode(),
@@ -726,6 +759,9 @@ public class BodyApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -816,6 +852,7 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEchoBodyFreeFormObjectResponseString", localVarResponse);
@@ -823,7 +860,8 @@ public class BodyApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -834,6 +872,9 @@ public class BodyApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -924,11 +965,13 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEchoBodyPet", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Pet>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -938,10 +981,9 @@ public class BodyApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Pet>(
             localVarResponse.statusCode(),
@@ -949,6 +991,9 @@ public class BodyApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1039,6 +1084,7 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEchoBodyPetResponseString", localVarResponse);
@@ -1046,7 +1092,8 @@ public class BodyApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -1057,6 +1104,9 @@ public class BodyApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1147,11 +1197,13 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEchoBodyStringEnum", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<StringEnumRef>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -1161,10 +1213,9 @@ public class BodyApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         StringEnumRef responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<StringEnumRef>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<StringEnumRef>(
             localVarResponse.statusCode(),
@@ -1172,6 +1223,9 @@ public class BodyApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1262,6 +1316,7 @@ public class BodyApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEchoBodyTagResponseString", localVarResponse);
@@ -1269,7 +1324,8 @@ public class BodyApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -1280,6 +1336,9 @@ public class BodyApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/api/FormApi.java

@@ -80,7 +80,7 @@ public class FormApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public FormApi() {
     this(Configuration.getDefaultApiClient());
@@ -98,7 +98,15 @@ public class FormApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -117,10 +125,13 @@ public class FormApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -218,6 +229,7 @@ public class FormApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testFormIntegerBooleanString", localVarResponse);
@@ -225,7 +237,8 @@ public class FormApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -236,6 +249,9 @@ public class FormApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -273,10 +289,11 @@ public class FormApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("POST", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -340,6 +357,7 @@ public class FormApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testFormObjectMultipart", localVarResponse);
@@ -347,7 +365,8 @@ public class FormApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -358,6 +377,9 @@ public class FormApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -411,8 +433,9 @@ public class FormApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
@@ -500,6 +523,7 @@ public class FormApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testFormOneof", localVarResponse);
@@ -507,7 +531,8 @@ public class FormApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -518,6 +543,9 @@ public class FormApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -564,10 +592,11 @@ public class FormApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("POST", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/api/HeaderApi.java

@@ -80,7 +80,7 @@ public class HeaderApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public HeaderApi() {
     this(Configuration.getDefaultApiClient());
@@ -98,7 +98,15 @@ public class HeaderApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -117,10 +125,13 @@ public class HeaderApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -226,6 +237,7 @@ public class HeaderApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testHeaderIntegerBooleanStringEnums", localVarResponse);
@@ -233,7 +245,8 @@ public class HeaderApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -244,6 +257,9 @@ public class HeaderApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/api/PathApi.java

@@ -80,7 +80,7 @@ public class PathApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public PathApi() {
     this(Configuration.getDefaultApiClient());
@@ -98,7 +98,15 @@ public class PathApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -117,10 +125,13 @@ public class PathApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -222,6 +233,7 @@ public class PathApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath", localVarResponse);
@@ -229,7 +241,8 @@ public class PathApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -240,6 +253,9 @@ public class PathApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/echo_api/java/native/src/main/java/org/openapitools/client/api/QueryApi.java

@@ -86,7 +86,7 @@ public class QueryApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public QueryApi() {
     this(Configuration.getDefaultApiClient());
@@ -104,7 +104,15 @@ public class QueryApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -123,10 +131,13 @@ public class QueryApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -220,6 +231,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEnumRefString", localVarResponse);
@@ -227,7 +239,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -238,6 +251,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -347,6 +363,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryDatetimeDateString", localVarResponse);
@@ -354,7 +371,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -365,6 +383,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -476,6 +497,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryIntegerBooleanString", localVarResponse);
@@ -483,7 +505,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -494,6 +517,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -597,6 +623,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleDeepObjectExplodeTrueObject", localVarResponse);
@@ -604,7 +631,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -615,6 +643,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -719,6 +750,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleDeepObjectExplodeTrueObjectAllOf", localVarResponse);
@@ -726,7 +758,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -737,6 +770,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -841,6 +877,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleFormExplodeFalseArrayInteger", localVarResponse);
@@ -848,7 +885,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -859,6 +897,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -958,6 +999,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleFormExplodeFalseArrayString", localVarResponse);
@@ -965,7 +1007,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -976,6 +1019,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1075,6 +1121,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleFormExplodeTrueArrayString", localVarResponse);
@@ -1082,7 +1129,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -1093,6 +1141,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1192,6 +1243,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleFormExplodeTrueObject", localVarResponse);
@@ -1199,7 +1251,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -1210,6 +1263,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1314,6 +1370,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleFormExplodeTrueObjectAllOf", localVarResponse);
@@ -1321,7 +1378,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -1332,6 +1390,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1435,6 +1496,7 @@ public class QueryApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryStyleJsonSerializationObject", localVarResponse);
@@ -1442,7 +1504,8 @@ public class QueryApi {
         // for plain text response
         if (localVarResponse.headers().map().containsKey("Content-Type") &&
                 "text/plain".equalsIgnoreCase(localVarResponse.headers().map().get("Content-Type").get(0).split(";")[0].trim())) {
-          java.util.Scanner s = new java.util.Scanner(localVarResponse.body()).useDelimiter("\\A");
+          localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+          java.util.Scanner s = new java.util.Scanner(localVarResponseBody == null ? InputStream.nullInputStream() : localVarResponseBody).useDelimiter("\\A");
           String responseBodyText = s.hasNext() ? s.next() : "";
           return new ApiResponse<String>(
                   localVarResponse.statusCode(),
@@ -1453,6 +1516,9 @@ public class QueryApi {
             throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
         }
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/ApiClient.java

@@ -20,6 +20,7 @@ import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import org.openapitools.jackson.nullable.JsonNullableModule;
 
 import java.io.InputStream;
+import java.io.IOException;
 import java.net.URI;
 import java.net.URLEncoder;
 import java.net.http.HttpClient;
@@ -34,6 +35,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.StringJoiner;
 import java.util.function.Consumer;
+import java.util.Optional;
+import java.util.zip.GZIPInputStream;
 import java.util.stream.Collectors;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -62,7 +65,7 @@ public class ApiClient {
   protected String basePath;
   protected Consumer<HttpRequest.Builder> interceptor;
   protected Consumer<HttpResponse<InputStream>> responseInterceptor;
-  protected Consumer<HttpResponse<String>> asyncResponseInterceptor;
+  protected Consumer<HttpResponse<InputStream>> asyncResponseInterceptor;
   protected Duration readTimeout;
   protected Duration connectTimeout;
 
@@ -384,7 +387,7 @@ public class ApiClient {
    *                    of null resets the interceptor to a no-op.
    * @return This object.
    */
-  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<String>> interceptor) {
+  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<InputStream>> interceptor) {
     this.asyncResponseInterceptor = interceptor;
     return this;
   }
@@ -394,7 +397,7 @@ public class ApiClient {
    *
    * @return The custom interceptor that was set, or null if there isn't any.
    */
-  public Consumer<HttpResponse<String>> getAsyncResponseInterceptor() {
+  public Consumer<HttpResponse<InputStream>> getAsyncResponseInterceptor() {
     return asyncResponseInterceptor;
   }
 
@@ -454,4 +457,32 @@ public class ApiClient {
   public Duration getConnectTimeout() {
     return connectTimeout;
   }
+
+  /**
+   * Returns the response body InputStream, transparently decoding gzip-compressed
+   * payloads when the server sets {@code Content-Encoding: gzip}.
+   *
+   * @param response HTTP response whose body should be consumed
+   * @return Original or decompressed InputStream for the response body
+   * @throws IOException if the response body cannot be accessed or wrapping fails
+   */
+  public static InputStream getResponseBody(HttpResponse<InputStream> response) throws IOException {
+    if (response == null) {
+      return null;
+    }
+    InputStream body = response.body();
+    if (body == null) {
+      return null;
+    }
+    Optional<String> encoding = response.headers().firstValue("Content-Encoding");
+    if (encoding.isPresent()) {
+      for (String token : encoding.get().split(",")) {
+        if ("gzip".equalsIgnoreCase(token.trim())) {
+          return new GZIPInputStream(body);
+        }
+      }
+    }
+    return body;
+  }
+
 }

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/api/AnotherFakeApi.java

@@ -76,7 +76,7 @@ public class AnotherFakeApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public AnotherFakeApi() {
     this(Configuration.getDefaultApiClient());
@@ -93,9 +93,19 @@ public class AnotherFakeApi {
   }
 
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
 
   private String formatExceptionMessage(String operationId, int statusCode, String body) {
@@ -112,10 +122,13 @@ public class AnotherFakeApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -174,22 +187,8 @@ public class AnotherFakeApi {
    */
   public CompletableFuture<Client> call123testSpecialTags(@javax.annotation.Nonnull Client client, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = call123testSpecialTagsRequestBuilder(client, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("call123testSpecialTags", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return call123testSpecialTagsWithHttpInfo(client, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -220,7 +219,7 @@ public class AnotherFakeApi {
       HttpRequest.Builder localVarRequestBuilder = call123testSpecialTagsRequestBuilder(client, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -228,13 +227,34 @@ public class AnotherFakeApi {
               return CompletableFuture.failedFuture(getApiException("call123testSpecialTags", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<Client>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<Client>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                Client responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Client>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/api/DefaultApi.java

@@ -76,7 +76,7 @@ public class DefaultApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public DefaultApi() {
     this(Configuration.getDefaultApiClient());
@@ -93,9 +93,19 @@ public class DefaultApi {
   }
 
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
 
   private String formatExceptionMessage(String operationId, int statusCode, String body) {
@@ -112,10 +122,13 @@ public class DefaultApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -172,22 +185,8 @@ public class DefaultApi {
    */
   public CompletableFuture<FooGetDefaultResponse> fooGet(Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = fooGetRequestBuilder(headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("fooGet", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<FooGetDefaultResponse>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return fooGetWithHttpInfo(headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -216,7 +215,7 @@ public class DefaultApi {
       HttpRequest.Builder localVarRequestBuilder = fooGetRequestBuilder(headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -224,13 +223,34 @@ public class DefaultApi {
               return CompletableFuture.failedFuture(getApiException("fooGet", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<FooGetDefaultResponse>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<FooGetDefaultResponse>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<FooGetDefaultResponse>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                FooGetDefaultResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<FooGetDefaultResponse>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<FooGetDefaultResponse>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/api/FakeClassnameTags123Api.java

@@ -82,7 +82,7 @@ public class FakeClassnameTags123Api {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public FakeClassnameTags123Api() {
     this(Configuration.getDefaultApiClient());
@@ -99,9 +99,19 @@ public class FakeClassnameTags123Api {
   }
 
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
 
   private String formatExceptionMessage(String operationId, int statusCode, String body) {
@@ -118,10 +128,13 @@ public class FakeClassnameTags123Api {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -180,22 +193,8 @@ public class FakeClassnameTags123Api {
    */
   public CompletableFuture<Client> testClassname(@javax.annotation.Nonnull Client client, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = testClassnameRequestBuilder(client, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("testClassname", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return testClassnameWithHttpInfo(client, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -226,7 +225,7 @@ public class FakeClassnameTags123Api {
       HttpRequest.Builder localVarRequestBuilder = testClassnameRequestBuilder(client, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -234,13 +233,34 @@ public class FakeClassnameTags123Api {
               return CompletableFuture.failedFuture(getApiException("testClassname", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<Client>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<Client>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                Client responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Client>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/api/PetApi.java

@@ -84,7 +84,7 @@ public class PetApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public PetApi() {
     this(Configuration.getDefaultApiClient());
@@ -101,9 +101,19 @@ public class PetApi {
   }
 
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
 
   private String formatExceptionMessage(String operationId, int statusCode, String body) {
@@ -120,10 +130,13 @@ public class PetApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -182,15 +195,8 @@ public class PetApi {
    */
   public CompletableFuture<Void> addPet(@javax.annotation.Nonnull Pet pet, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = addPetRequestBuilder(pet, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("addPet", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return addPetWithHttpInfo(pet, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -221,16 +227,30 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = addPetRequestBuilder(pet, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("addPet", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -294,15 +314,8 @@ public class PetApi {
    */
   public CompletableFuture<Void> deletePet(@javax.annotation.Nonnull Long petId, @javax.annotation.Nullable String apiKey, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = deletePetRequestBuilder(petId, apiKey, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("deletePet", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return deletePetWithHttpInfo(petId, apiKey, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -335,16 +348,30 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = deletePetRequestBuilder(petId, apiKey, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("deletePet", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -404,22 +431,8 @@ public class PetApi {
    */
   public CompletableFuture<List<Pet>> findPetsByStatus(@javax.annotation.Nonnull List<String> status, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = findPetsByStatusRequestBuilder(status, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("findPetsByStatus", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return findPetsByStatusWithHttpInfo(status, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -450,7 +463,7 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = findPetsByStatusRequestBuilder(status, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -458,13 +471,34 @@ public class PetApi {
               return CompletableFuture.failedFuture(getApiException("findPetsByStatus", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<List<Pet>>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<List<Pet>>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                List<Pet> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<List<Pet>>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -542,22 +576,8 @@ public class PetApi {
   @Deprecated
   public CompletableFuture<List<Pet>> findPetsByTags(@javax.annotation.Nonnull List<String> tags, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = findPetsByTagsRequestBuilder(tags, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("findPetsByTags", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return findPetsByTagsWithHttpInfo(tags, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -592,7 +612,7 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = findPetsByTagsRequestBuilder(tags, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -600,13 +620,34 @@ public class PetApi {
               return CompletableFuture.failedFuture(getApiException("findPetsByTags", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<List<Pet>>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<List<Pet>>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                List<Pet> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<List<Pet>>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -680,22 +721,8 @@ public class PetApi {
    */
   public CompletableFuture<Pet> getPetById(@javax.annotation.Nonnull Long petId, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = getPetByIdRequestBuilder(petId, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("getPetById", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return getPetByIdWithHttpInfo(petId, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -726,7 +753,7 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = getPetByIdRequestBuilder(petId, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -734,13 +761,34 @@ public class PetApi {
               return CompletableFuture.failedFuture(getApiException("getPetById", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<Pet>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<Pet>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Pet>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -800,15 +848,8 @@ public class PetApi {
    */
   public CompletableFuture<Void> updatePet(@javax.annotation.Nonnull Pet pet, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = updatePetRequestBuilder(pet, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("updatePet", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return updatePetWithHttpInfo(pet, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -839,16 +880,30 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = updatePetRequestBuilder(pet, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("updatePet", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -914,15 +969,8 @@ public class PetApi {
    */
   public CompletableFuture<Void> updatePetWithForm(@javax.annotation.Nonnull Long petId, @javax.annotation.Nullable String name, @javax.annotation.Nullable String status, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = updatePetWithFormRequestBuilder(petId, name, status, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("updatePetWithForm", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return updatePetWithFormWithHttpInfo(petId, name, status, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -957,16 +1005,30 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = updatePetWithFormRequestBuilder(petId, name, status, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("updatePetWithForm", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -1004,10 +1066,11 @@ public class PetApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("POST", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -1044,22 +1107,8 @@ public class PetApi {
    */
   public CompletableFuture<ModelApiResponse> uploadFile(@javax.annotation.Nonnull Long petId, @javax.annotation.Nullable String additionalMetadata, @javax.annotation.Nullable File _file, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = uploadFileRequestBuilder(petId, additionalMetadata, _file, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("uploadFile", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return uploadFileWithHttpInfo(petId, additionalMetadata, _file, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -1094,7 +1143,7 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = uploadFileRequestBuilder(petId, additionalMetadata, _file, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -1102,13 +1151,34 @@ public class PetApi {
               return CompletableFuture.failedFuture(getApiException("uploadFile", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<ModelApiResponse>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<ModelApiResponse>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                ModelApiResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<ModelApiResponse>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -1166,8 +1236,9 @@ public class PetApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
@@ -1208,22 +1279,8 @@ public class PetApi {
    */
   public CompletableFuture<ModelApiResponse> uploadFileWithRequiredFile(@javax.annotation.Nonnull Long petId, @javax.annotation.Nonnull File requiredFile, @javax.annotation.Nullable String additionalMetadata, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = uploadFileWithRequiredFileRequestBuilder(petId, requiredFile, additionalMetadata, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("uploadFileWithRequiredFile", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return uploadFileWithRequiredFileWithHttpInfo(petId, requiredFile, additionalMetadata, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -1258,7 +1315,7 @@ public class PetApi {
       HttpRequest.Builder localVarRequestBuilder = uploadFileWithRequiredFileRequestBuilder(petId, requiredFile, additionalMetadata, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -1266,13 +1323,34 @@ public class PetApi {
               return CompletableFuture.failedFuture(getApiException("uploadFileWithRequiredFile", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<ModelApiResponse>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<ModelApiResponse>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                ModelApiResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<ModelApiResponse>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -1334,8 +1412,9 @@ public class PetApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/api/StoreApi.java

@@ -82,7 +82,7 @@ public class StoreApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public StoreApi() {
     this(Configuration.getDefaultApiClient());
@@ -99,9 +99,19 @@ public class StoreApi {
   }
 
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
 
   private String formatExceptionMessage(String operationId, int statusCode, String body) {
@@ -118,10 +128,13 @@ public class StoreApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -180,15 +193,8 @@ public class StoreApi {
    */
   public CompletableFuture<Void> deleteOrder(@javax.annotation.Nonnull String orderId, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = deleteOrderRequestBuilder(orderId, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("deleteOrder", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return deleteOrderWithHttpInfo(orderId, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -219,16 +225,30 @@ public class StoreApi {
       HttpRequest.Builder localVarRequestBuilder = deleteOrderRequestBuilder(orderId, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("deleteOrder", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -283,22 +303,8 @@ public class StoreApi {
    */
   public CompletableFuture<Map<String, Integer>> getInventory(Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = getInventoryRequestBuilder(headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("getInventory", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Map<String, Integer>>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return getInventoryWithHttpInfo(headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -327,7 +333,7 @@ public class StoreApi {
       HttpRequest.Builder localVarRequestBuilder = getInventoryRequestBuilder(headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -335,13 +341,34 @@ public class StoreApi {
               return CompletableFuture.failedFuture(getApiException("getInventory", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<Map<String, Integer>>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Map<String, Integer>>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<Map<String, Integer>>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                Map<String, Integer> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Map<String, Integer>>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Map<String, Integer>>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -396,22 +423,8 @@ public class StoreApi {
    */
   public CompletableFuture<Order> getOrderById(@javax.annotation.Nonnull Long orderId, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = getOrderByIdRequestBuilder(orderId, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("getOrderById", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return getOrderByIdWithHttpInfo(orderId, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -442,7 +455,7 @@ public class StoreApi {
       HttpRequest.Builder localVarRequestBuilder = getOrderByIdRequestBuilder(orderId, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -450,13 +463,34 @@ public class StoreApi {
               return CompletableFuture.failedFuture(getApiException("getOrderById", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<Order>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<Order>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                Order responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Order>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -516,22 +550,8 @@ public class StoreApi {
    */
   public CompletableFuture<Order> placeOrder(@javax.annotation.Nonnull Order order, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = placeOrderRequestBuilder(order, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("placeOrder", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return placeOrderWithHttpInfo(order, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -562,7 +582,7 @@ public class StoreApi {
       HttpRequest.Builder localVarRequestBuilder = placeOrderRequestBuilder(order, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -570,13 +590,34 @@ public class StoreApi {
               return CompletableFuture.failedFuture(getApiException("placeOrder", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<Order>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<Order>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                Order responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Order>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/api/UserApi.java

@@ -83,7 +83,7 @@ public class UserApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public UserApi() {
     this(Configuration.getDefaultApiClient());
@@ -100,9 +100,19 @@ public class UserApi {
   }
 
 
-  private ApiException getApiException(String operationId, HttpResponse<String> response) {
-    String message = formatExceptionMessage(operationId, response.statusCode(), response.body());
-    return new ApiException(response.statusCode(), message, response.headers(), response.body());
+  private ApiException getApiException(String operationId, HttpResponse<InputStream> response) {
+    try {
+      InputStream responseBody = ApiClient.getResponseBody(response);
+      String body = null;
+      if (responseBody != null) {
+        body = new String(responseBody.readAllBytes());
+        responseBody.close();
+      }
+      String message = formatExceptionMessage(operationId, response.statusCode(), body);
+      return new ApiException(response.statusCode(), message, response.headers(), body);
+    } catch (IOException e) {
+      return new ApiException(e);
+    }
   }
 
   private String formatExceptionMessage(String operationId, int statusCode, String body) {
@@ -119,10 +129,13 @@ public class UserApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -181,15 +194,8 @@ public class UserApi {
    */
   public CompletableFuture<Void> createUser(@javax.annotation.Nonnull User user, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = createUserRequestBuilder(user, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("createUser", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return createUserWithHttpInfo(user, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -220,16 +226,30 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = createUserRequestBuilder(user, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("createUser", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -291,15 +311,8 @@ public class UserApi {
    */
   public CompletableFuture<Void> createUsersWithArrayInput(@javax.annotation.Nonnull List<User> user, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = createUsersWithArrayInputRequestBuilder(user, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("createUsersWithArrayInput", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return createUsersWithArrayInputWithHttpInfo(user, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -330,16 +343,30 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = createUsersWithArrayInputRequestBuilder(user, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("createUsersWithArrayInput", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -401,15 +428,8 @@ public class UserApi {
    */
   public CompletableFuture<Void> createUsersWithListInput(@javax.annotation.Nonnull List<User> user, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = createUsersWithListInputRequestBuilder(user, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("createUsersWithListInput", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return createUsersWithListInputWithHttpInfo(user, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -440,16 +460,30 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = createUsersWithListInputRequestBuilder(user, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("createUsersWithListInput", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -511,15 +545,8 @@ public class UserApi {
    */
   public CompletableFuture<Void> deleteUser(@javax.annotation.Nonnull String username, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = deleteUserRequestBuilder(username, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("deleteUser", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return deleteUserWithHttpInfo(username, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -550,16 +577,30 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = deleteUserRequestBuilder(username, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("deleteUser", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -616,22 +657,8 @@ public class UserApi {
    */
   public CompletableFuture<User> getUserByName(@javax.annotation.Nonnull String username, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = getUserByNameRequestBuilder(username, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("getUserByName", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<User>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return getUserByNameWithHttpInfo(username, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -662,7 +689,7 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = getUserByNameRequestBuilder(username, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -670,13 +697,34 @@ public class UserApi {
               return CompletableFuture.failedFuture(getApiException("getUserByName", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<User>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<User>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<User>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                User responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<User>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<User>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -738,22 +786,8 @@ public class UserApi {
    */
   public CompletableFuture<String> loginUser(@javax.annotation.Nonnull String username, @javax.annotation.Nonnull String password, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = loginUserRequestBuilder(username, password, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("loginUser", localVarResponse));
-            }
-            try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<String>() {})
-              );
-            } catch (IOException e) {
-              return CompletableFuture.failedFuture(new ApiException(e));
-            }
-      });
+      return loginUserWithHttpInfo(username, password, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -786,7 +820,7 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = loginUserRequestBuilder(username, password, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
@@ -794,13 +828,34 @@ public class UserApi {
               return CompletableFuture.failedFuture(getApiException("loginUser", localVarResponse));
             }
             try {
-              String responseBody = localVarResponse.body();
-              return CompletableFuture.completedFuture(
-                  new ApiResponse<String>(
-                      localVarResponse.statusCode(),
-                      localVarResponse.headers().map(),
-                      responseBody == null || responseBody.isBlank() ? null : memberVarObjectMapper.readValue(responseBody, new TypeReference<String>() {}))
-              );
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody == null) {
+                  return CompletableFuture.completedFuture(
+                      new ApiResponse<String>(
+                          localVarResponse.statusCode(),
+                          localVarResponse.headers().map(),
+                          null
+                      )
+                  );
+                }
+                
+                
+                String responseBody = new String(localVarResponseBody.readAllBytes());
+                String responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<String>() {});
+                
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<String>(
+                        localVarResponse.statusCode(),
+                        localVarResponse.headers().map(),
+                        responseValue
+                    )
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
             } catch (IOException e) {
               return CompletableFuture.failedFuture(new ApiException(e));
             }
@@ -878,15 +933,8 @@ public class UserApi {
    */
   public CompletableFuture<Void> logoutUser(Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = logoutUserRequestBuilder(headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("logoutUser", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return logoutUserWithHttpInfo(headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -915,16 +963,30 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = logoutUserRequestBuilder(headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("logoutUser", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }
@@ -978,15 +1040,8 @@ public class UserApi {
    */
   public CompletableFuture<Void> updateUser(@javax.annotation.Nonnull String username, @javax.annotation.Nonnull User user, Map<String, String> headers) throws ApiException {
     try {
-      HttpRequest.Builder localVarRequestBuilder = updateUserRequestBuilder(username, user, headers);
-      return memberVarHttpClient.sendAsync(
-          localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
-            if (localVarResponse.statusCode()/ 100 != 2) {
-              return CompletableFuture.failedFuture(getApiException("updateUser", localVarResponse));
-            }
-            return CompletableFuture.completedFuture(null);
-      });
+      return updateUserWithHttpInfo(username, user, headers)
+          .thenApply(ApiResponse::getData);
     }
     catch (ApiException e) {
       return CompletableFuture.failedFuture(e);
@@ -1019,16 +1074,30 @@ public class UserApi {
       HttpRequest.Builder localVarRequestBuilder = updateUserRequestBuilder(username, user, headers);
       return memberVarHttpClient.sendAsync(
           localVarRequestBuilder.build(),
-          HttpResponse.BodyHandlers.ofString()).thenComposeAsync(localVarResponse -> {
+          HttpResponse.BodyHandlers.ofInputStream()).thenComposeAsync(localVarResponse -> {
             if (memberVarAsyncResponseInterceptor != null) {
               memberVarAsyncResponseInterceptor.accept(localVarResponse);
             }
             if (localVarResponse.statusCode()/ 100 != 2) {
               return CompletableFuture.failedFuture(getApiException("updateUser", localVarResponse));
             }
-            return CompletableFuture.completedFuture(
-                new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
-            );
+            try {
+              InputStream localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+              try {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.readAllBytes();
+                }
+                return CompletableFuture.completedFuture(
+                    new ApiResponse<Void>(localVarResponse.statusCode(), localVarResponse.headers().map(), null)
+                );
+              } finally {
+                if (localVarResponseBody != null) {
+                  localVarResponseBody.close();
+                }
+              }
+            } catch (IOException e) {
+              return CompletableFuture.failedFuture(new ApiException(e));
+            }
         }
       );
     }

samples/client/petstore/java/native-jakarta/src/main/java/org/openapitools/client/ApiClient.java

@@ -20,6 +20,7 @@ import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import org.openapitools.jackson.nullable.JsonNullableModule;
 
 import java.io.InputStream;
+import java.io.IOException;
 import java.net.URI;
 import java.net.URLEncoder;
 import java.net.http.HttpClient;
@@ -34,6 +35,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.StringJoiner;
 import java.util.function.Consumer;
+import java.util.Optional;
+import java.util.zip.GZIPInputStream;
 import java.util.stream.Collectors;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -62,7 +65,7 @@ public class ApiClient {
   protected String basePath;
   protected Consumer<HttpRequest.Builder> interceptor;
   protected Consumer<HttpResponse<InputStream>> responseInterceptor;
-  protected Consumer<HttpResponse<String>> asyncResponseInterceptor;
+  protected Consumer<HttpResponse<InputStream>> asyncResponseInterceptor;
   protected Duration readTimeout;
   protected Duration connectTimeout;
 
@@ -384,7 +387,7 @@ public class ApiClient {
    *                    of null resets the interceptor to a no-op.
    * @return This object.
    */
-  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<String>> interceptor) {
+  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<InputStream>> interceptor) {
     this.asyncResponseInterceptor = interceptor;
     return this;
   }
@@ -394,7 +397,7 @@ public class ApiClient {
    *
    * @return The custom interceptor that was set, or null if there isn't any.
    */
-  public Consumer<HttpResponse<String>> getAsyncResponseInterceptor() {
+  public Consumer<HttpResponse<InputStream>> getAsyncResponseInterceptor() {
     return asyncResponseInterceptor;
   }
 
@@ -454,4 +457,32 @@ public class ApiClient {
   public Duration getConnectTimeout() {
     return connectTimeout;
   }
+
+  /**
+   * Returns the response body InputStream, transparently decoding gzip-compressed
+   * payloads when the server sets {@code Content-Encoding: gzip}.
+   *
+   * @param response HTTP response whose body should be consumed
+   * @return Original or decompressed InputStream for the response body
+   * @throws IOException if the response body cannot be accessed or wrapping fails
+   */
+  public static InputStream getResponseBody(HttpResponse<InputStream> response) throws IOException {
+    if (response == null) {
+      return null;
+    }
+    InputStream body = response.body();
+    if (body == null) {
+      return null;
+    }
+    Optional<String> encoding = response.headers().firstValue("Content-Encoding");
+    if (encoding.isPresent()) {
+      for (String token : encoding.get().split(",")) {
+        if ("gzip".equalsIgnoreCase(token.trim())) {
+          return new GZIPInputStream(body);
+        }
+      }
+    }
+    return body;
+  }
+
 }

samples/client/petstore/java/native-jakarta/src/main/java/org/openapitools/client/api/PetApi.java

@@ -82,7 +82,7 @@ public class PetApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public PetApi() {
     this(Configuration.getDefaultApiClient());
@@ -100,7 +100,15 @@ public class PetApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -119,10 +127,13 @@ public class PetApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -212,11 +223,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("addPet", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Pet>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -226,10 +239,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Pet>(
             localVarResponse.statusCode(),
@@ -237,6 +249,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -332,21 +347,24 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("deletePet", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -439,11 +457,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("findPetsByStatus", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<List<Pet>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -453,10 +473,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         List<Pet> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<List<Pet>>(
             localVarResponse.statusCode(),
@@ -464,6 +483,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -575,11 +597,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("findPetsByTags", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<List<Pet>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -589,10 +613,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         List<Pet> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<List<Pet>>(
             localVarResponse.statusCode(),
@@ -600,6 +623,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -703,11 +729,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getPetById", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Pet>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -717,10 +745,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Pet>(
             localVarResponse.statusCode(),
@@ -728,6 +755,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -825,11 +855,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("updatePet", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Pet>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -839,10 +871,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Pet>(
             localVarResponse.statusCode(),
@@ -850,6 +881,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -949,21 +983,24 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("updatePetWithForm", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1003,10 +1040,11 @@ public class PetApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("POST", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -1078,11 +1116,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("uploadFile", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<ModelApiResponse>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -1092,10 +1132,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         ModelApiResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<ModelApiResponse>(
             localVarResponse.statusCode(),
@@ -1103,6 +1142,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1159,8 +1201,9 @@ public class PetApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())

samples/client/petstore/java/native-jakarta/src/main/java/org/openapitools/client/api/StoreApi.java

@@ -80,7 +80,7 @@ public class StoreApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public StoreApi() {
     this(Configuration.getDefaultApiClient());
@@ -98,7 +98,15 @@ public class StoreApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -117,10 +125,13 @@ public class StoreApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -207,21 +218,24 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("deleteOrder", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -307,11 +321,13 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getInventory", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Map<String, Integer>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -321,10 +337,9 @@ public class StoreApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Map<String, Integer> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Map<String, Integer>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Map<String, Integer>>(
             localVarResponse.statusCode(),
@@ -332,6 +347,9 @@ public class StoreApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -416,11 +434,13 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getOrderById", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Order>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -430,10 +450,9 @@ public class StoreApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Order responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Order>(
             localVarResponse.statusCode(),
@@ -441,6 +460,9 @@ public class StoreApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -530,11 +552,13 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("placeOrder", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Order>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -544,10 +568,9 @@ public class StoreApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Order responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Order>(
             localVarResponse.statusCode(),
@@ -555,6 +578,9 @@ public class StoreApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native-jakarta/src/main/java/org/openapitools/client/api/UserApi.java

@@ -81,7 +81,7 @@ public class UserApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public UserApi() {
     this(Configuration.getDefaultApiClient());
@@ -99,7 +99,15 @@ public class UserApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -118,10 +126,13 @@ public class UserApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -208,21 +219,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("createUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -314,21 +328,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("createUsersWithArrayInput", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -420,21 +437,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("createUsersWithListInput", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -526,21 +546,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("deleteUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -630,11 +653,13 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getUserByName", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<User>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -644,10 +669,9 @@ public class UserApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         User responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<User>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<User>(
             localVarResponse.statusCode(),
@@ -655,6 +679,9 @@ public class UserApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -748,11 +775,13 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("loginUser", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<String>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -762,10 +791,9 @@ public class UserApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         String responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<String>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<String>(
             localVarResponse.statusCode(),
@@ -773,6 +801,9 @@ public class UserApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -875,21 +906,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("logoutUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -975,21 +1009,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("updateUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native/src/main/java/org/openapitools/client/ApiClient.java

@@ -20,6 +20,7 @@ import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import org.openapitools.jackson.nullable.JsonNullableModule;
 
 import java.io.InputStream;
+import java.io.IOException;
 import java.net.URI;
 import java.net.URLEncoder;
 import java.net.http.HttpClient;
@@ -34,6 +35,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.StringJoiner;
 import java.util.function.Consumer;
+import java.util.Optional;
+import java.util.zip.GZIPInputStream;
 import java.util.stream.Collectors;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -62,7 +65,7 @@ public class ApiClient {
   protected String basePath;
   protected Consumer<HttpRequest.Builder> interceptor;
   protected Consumer<HttpResponse<InputStream>> responseInterceptor;
-  protected Consumer<HttpResponse<String>> asyncResponseInterceptor;
+  protected Consumer<HttpResponse<InputStream>> asyncResponseInterceptor;
   protected Duration readTimeout;
   protected Duration connectTimeout;
 
@@ -384,7 +387,7 @@ public class ApiClient {
    *                    of null resets the interceptor to a no-op.
    * @return This object.
    */
-  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<String>> interceptor) {
+  public ApiClient setAsyncResponseInterceptor(Consumer<HttpResponse<InputStream>> interceptor) {
     this.asyncResponseInterceptor = interceptor;
     return this;
   }
@@ -394,7 +397,7 @@ public class ApiClient {
    *
    * @return The custom interceptor that was set, or null if there isn't any.
    */
-  public Consumer<HttpResponse<String>> getAsyncResponseInterceptor() {
+  public Consumer<HttpResponse<InputStream>> getAsyncResponseInterceptor() {
     return asyncResponseInterceptor;
   }
 
@@ -454,4 +457,32 @@ public class ApiClient {
   public Duration getConnectTimeout() {
     return connectTimeout;
   }
+
+  /**
+   * Returns the response body InputStream, transparently decoding gzip-compressed
+   * payloads when the server sets {@code Content-Encoding: gzip}.
+   *
+   * @param response HTTP response whose body should be consumed
+   * @return Original or decompressed InputStream for the response body
+   * @throws IOException if the response body cannot be accessed or wrapping fails
+   */
+  public static InputStream getResponseBody(HttpResponse<InputStream> response) throws IOException {
+    if (response == null) {
+      return null;
+    }
+    InputStream body = response.body();
+    if (body == null) {
+      return null;
+    }
+    Optional<String> encoding = response.headers().firstValue("Content-Encoding");
+    if (encoding.isPresent()) {
+      for (String token : encoding.get().split(",")) {
+        if ("gzip".equalsIgnoreCase(token.trim())) {
+          return new GZIPInputStream(body);
+        }
+      }
+    }
+    return body;
+  }
+
 }

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/AnotherFakeApi.java

@@ -74,7 +74,7 @@ public class AnotherFakeApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public AnotherFakeApi() {
     this(Configuration.getDefaultApiClient());
@@ -92,7 +92,15 @@ public class AnotherFakeApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -111,10 +119,13 @@ public class AnotherFakeApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -204,11 +215,13 @@ public class AnotherFakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("call123testSpecialTags", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Client>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -218,10 +231,9 @@ public class AnotherFakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Client responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Client>(
             localVarResponse.statusCode(),
@@ -229,6 +241,9 @@ public class AnotherFakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/DefaultApi.java

@@ -74,7 +74,7 @@ public class DefaultApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public DefaultApi() {
     this(Configuration.getDefaultApiClient());
@@ -92,7 +92,15 @@ public class DefaultApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -111,10 +119,13 @@ public class DefaultApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -200,11 +211,13 @@ public class DefaultApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fooGet", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<FooGetDefaultResponse>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -214,10 +227,9 @@ public class DefaultApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         FooGetDefaultResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<FooGetDefaultResponse>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<FooGetDefaultResponse>(
             localVarResponse.statusCode(),
@@ -225,6 +237,9 @@ public class DefaultApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/FakeApi.java

@@ -91,7 +91,7 @@ public class FakeApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public FakeApi() {
     this(Configuration.getDefaultApiClient());
@@ -109,7 +109,15 @@ public class FakeApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -128,10 +136,13 @@ public class FakeApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -217,11 +228,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fakeBigDecimalMap", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<FakeBigDecimalMap200Response>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -231,10 +244,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         FakeBigDecimalMap200Response responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<FakeBigDecimalMap200Response>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<FakeBigDecimalMap200Response>(
             localVarResponse.statusCode(),
@@ -242,6 +254,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -322,11 +337,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fakeHealthGet", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<HealthCheckResult>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -336,10 +353,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         HealthCheckResult responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<HealthCheckResult>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<HealthCheckResult>(
             localVarResponse.statusCode(),
@@ -347,6 +363,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -431,11 +450,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fakeOuterBooleanSerialize", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Boolean>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -445,10 +466,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Boolean responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Boolean>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Boolean>(
             localVarResponse.statusCode(),
@@ -456,6 +476,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -546,11 +569,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fakeOuterCompositeSerialize", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<OuterComposite>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -560,10 +585,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         OuterComposite responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<OuterComposite>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<OuterComposite>(
             localVarResponse.statusCode(),
@@ -571,6 +595,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -661,11 +688,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fakeOuterNumberSerialize", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<BigDecimal>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -675,10 +704,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         BigDecimal responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<BigDecimal>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<BigDecimal>(
             localVarResponse.statusCode(),
@@ -686,6 +714,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -776,11 +807,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("fakeOuterStringSerialize", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<String>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -790,10 +823,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         String responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<String>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<String>(
             localVarResponse.statusCode(),
@@ -801,6 +833,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -882,11 +917,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getApplicationJsonUtf8", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<List<OuterEnum>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -896,10 +933,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         List<OuterEnum> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<OuterEnum>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<List<OuterEnum>>(
             localVarResponse.statusCode(),
@@ -907,6 +943,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -987,11 +1026,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getArrayOfEnums", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<List<OuterEnum>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -1001,10 +1042,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         List<OuterEnum> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<OuterEnum>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<List<OuterEnum>>(
             localVarResponse.statusCode(),
@@ -1012,6 +1052,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1093,21 +1136,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testAdditionalPropertiesReference", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1199,21 +1245,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testBodyWithFileSchema", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1309,21 +1358,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testBodyWithQueryParams", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1437,11 +1489,13 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testClientModel", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Client>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -1451,10 +1505,9 @@ public class FakeApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Client responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Client>(
             localVarResponse.statusCode(),
@@ -1462,6 +1515,9 @@ public class FakeApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1605,21 +1661,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEndpointParameters", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1706,10 +1765,11 @@ public class FakeApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("POST", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -1798,21 +1858,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testEnumParameters", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1876,10 +1939,11 @@ public class FakeApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("GET", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -2022,21 +2086,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testGroupParameters", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -2246,21 +2313,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testInlineAdditionalProperties", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -2352,21 +2422,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testInlineFreeformAdditionalProperties", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -2462,21 +2535,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testJsonFormData", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -2519,10 +2595,11 @@ public class FakeApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("GET", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -2599,21 +2676,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testQueryParameterCollectionFormat", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -2738,21 +2818,24 @@ public class FakeApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testStringMapReference", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/FakeClassnameTags123Api.java

@@ -80,7 +80,7 @@ public class FakeClassnameTags123Api {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public FakeClassnameTags123Api() {
     this(Configuration.getDefaultApiClient());
@@ -98,7 +98,15 @@ public class FakeClassnameTags123Api {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -117,10 +125,13 @@ public class FakeClassnameTags123Api {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -210,11 +221,13 @@ public class FakeClassnameTags123Api {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("testClassname", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Client>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -224,10 +237,9 @@ public class FakeClassnameTags123Api {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Client responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Client>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Client>(
             localVarResponse.statusCode(),
@@ -235,6 +247,9 @@ public class FakeClassnameTags123Api {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/PetApi.java

@@ -82,7 +82,7 @@ public class PetApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public PetApi() {
     this(Configuration.getDefaultApiClient());
@@ -100,7 +100,15 @@ public class PetApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -119,10 +127,13 @@ public class PetApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -209,21 +220,24 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("addPet", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -319,21 +333,24 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("deletePet", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -426,11 +443,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("findPetsByStatus", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<List<Pet>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -440,10 +459,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         List<Pet> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<List<Pet>>(
             localVarResponse.statusCode(),
@@ -451,6 +469,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -562,11 +583,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("findPetsByTags", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<List<Pet>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -576,10 +599,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         List<Pet> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<List<Pet>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<List<Pet>>(
             localVarResponse.statusCode(),
@@ -587,6 +609,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -690,11 +715,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getPetById", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Pet>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -704,10 +731,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Pet responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Pet>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Pet>(
             localVarResponse.statusCode(),
@@ -715,6 +741,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -801,21 +830,24 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("updatePet", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -915,21 +947,24 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("updatePetWithForm", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -969,10 +1004,11 @@ public class PetApi {
     } catch (IOException e) {
         throw new RuntimeException(e);
     }
+    byte[] formBytes = formOutputStream.toByteArray();
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
         .method("POST", HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes)));
     if (memberVarReadTimeout != null) {
       localVarRequestBuilder.timeout(memberVarReadTimeout);
     }
@@ -1044,11 +1080,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("uploadFile", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<ModelApiResponse>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -1058,10 +1096,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         ModelApiResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<ModelApiResponse>(
             localVarResponse.statusCode(),
@@ -1069,6 +1106,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1125,8 +1165,9 @@ public class PetApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())
@@ -1202,11 +1243,13 @@ public class PetApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("uploadFileWithRequiredFile", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<ModelApiResponse>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -1216,10 +1259,9 @@ public class PetApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         ModelApiResponse responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<ModelApiResponse>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<ModelApiResponse>(
             localVarResponse.statusCode(),
@@ -1227,6 +1269,9 @@ public class PetApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -1287,8 +1332,9 @@ public class PetApi {
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
+        byte[] formBytes = formOutputStream.toByteArray();
         formDataPublisher = HttpRequest.BodyPublishers
-            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+            .ofInputStream(() -> new ByteArrayInputStream(formBytes));
     }
     localVarRequestBuilder
         .header("Content-Type", entity.getContentType().getValue())

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/StoreApi.java

@@ -80,7 +80,7 @@ public class StoreApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public StoreApi() {
     this(Configuration.getDefaultApiClient());
@@ -98,7 +98,15 @@ public class StoreApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -117,10 +125,13 @@ public class StoreApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -207,21 +218,24 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("deleteOrder", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -307,11 +321,13 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getInventory", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Map<String, Integer>>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -321,10 +337,9 @@ public class StoreApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Map<String, Integer> responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Map<String, Integer>>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Map<String, Integer>>(
             localVarResponse.statusCode(),
@@ -332,6 +347,9 @@ public class StoreApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -416,11 +434,13 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getOrderById", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Order>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -430,10 +450,9 @@ public class StoreApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Order responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Order>(
             localVarResponse.statusCode(),
@@ -441,6 +460,9 @@ public class StoreApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -530,11 +552,13 @@ public class StoreApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("placeOrder", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<Order>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -544,10 +568,9 @@ public class StoreApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         Order responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<Order>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<Order>(
             localVarResponse.statusCode(),
@@ -555,6 +578,9 @@ public class StoreApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);

samples/client/petstore/java/native/src/main/java/org/openapitools/client/api/UserApi.java

@@ -81,7 +81,7 @@ public class UserApi {
   private final Consumer<HttpRequest.Builder> memberVarInterceptor;
   private final Duration memberVarReadTimeout;
   private final Consumer<HttpResponse<InputStream>> memberVarResponseInterceptor;
-  private final Consumer<HttpResponse<String>> memberVarAsyncResponseInterceptor;
+  private final Consumer<HttpResponse<InputStream>> memberVarAsyncResponseInterceptor;
 
   public UserApi() {
     this(Configuration.getDefaultApiClient());
@@ -99,7 +99,15 @@ public class UserApi {
 
 
   protected ApiException getApiException(String operationId, HttpResponse<InputStream> response) throws IOException {
-    String body = response.body() == null ? null : new String(response.body().readAllBytes());
+    InputStream responseBody = ApiClient.getResponseBody(response);
+    String body = null;
+    try {
+      body = responseBody == null ? null : new String(responseBody.readAllBytes());
+    } finally {
+      if (responseBody != null) {
+        responseBody.close();
+      }
+    }
     String message = formatExceptionMessage(operationId, response.statusCode(), body);
     return new ApiException(response.statusCode(), message, response.headers(), body);
   }
@@ -118,10 +126,13 @@ public class UserApi {
    * @return File
    * @throws ApiException If fail to read file content from response and write to disk
    */
-  public File downloadFileFromResponse(HttpResponse<InputStream> response) throws ApiException {
+  public File downloadFileFromResponse(HttpResponse<InputStream> response, InputStream responseBody) throws ApiException {
+    if (responseBody == null) {
+      throw new ApiException(new IOException("Response body is empty"));
+    }
     try {
       File file = prepareDownloadFile(response);
-      java.nio.file.Files.copy(response.body(), file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
+      java.nio.file.Files.copy(responseBody, file.toPath(), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
       return file;
     } catch (IOException e) {
       throw new ApiException(e);
@@ -208,21 +219,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("createUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -314,21 +328,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("createUsersWithArrayInput", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -420,21 +437,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("createUsersWithListInput", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -526,21 +546,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("deleteUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -630,11 +653,13 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("getUserByName", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<User>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -644,10 +669,9 @@ public class UserApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         User responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<User>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<User>(
             localVarResponse.statusCode(),
@@ -655,6 +679,9 @@ public class UserApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -748,11 +775,13 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("loginUser", localVarResponse);
         }
-        if (localVarResponse.body() == null) {
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody == null) {
           return new ApiResponse<String>(
               localVarResponse.statusCode(),
               localVarResponse.headers().map(),
@@ -762,10 +791,9 @@ public class UserApi {
 
         
         
-        String responseBody = new String(localVarResponse.body().readAllBytes());
+        String responseBody = new String(localVarResponseBody.readAllBytes());
         String responseValue = responseBody.isBlank()? null: memberVarObjectMapper.readValue(responseBody, new TypeReference<String>() {});
         
-        localVarResponse.body().close();
 
         return new ApiResponse<String>(
             localVarResponse.statusCode(),
@@ -773,6 +801,9 @@ public class UserApi {
             responseValue
         );
       } finally {
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
+        }
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -875,21 +906,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("logoutUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);
@@ -975,21 +1009,24 @@ public class UserApi {
       if (memberVarResponseInterceptor != null) {
         memberVarResponseInterceptor.accept(localVarResponse);
       }
+      InputStream localVarResponseBody = null;
       try {
         if (localVarResponse.statusCode()/ 100 != 2) {
           throw getApiException("updateUser", localVarResponse);
         }
+        localVarResponseBody = ApiClient.getResponseBody(localVarResponse);
+        if (localVarResponseBody != null) {
+          localVarResponseBody.readAllBytes();
+        }
         return new ApiResponse<>(
             localVarResponse.statusCode(),
             localVarResponse.headers().map(),
             null
         );
       } finally {
-        // Drain the InputStream
-        while (localVarResponse.body().read() != -1) {
-          // Ignore
+        if (localVarResponseBody != null) {
+          localVarResponseBody.close();
         }
-        localVarResponse.body().close();
       }
     } catch (IOException e) {
       throw new ApiException(e);