[Java][Native] Fix multipart builder files array (#16055) (#16094)

* [Java] Fixed bug in native client generation when API accepts array of files (#16055)

* Adding test for java native client

* Updated samples

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

@@ -24,6 +24,12 @@ import org.openapitools.client.model.Tag;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import org.apache.http.HttpEntity;
+import org.apache.http.NameValuePair;
+import org.apache.http.entity.mime.MultipartEntityBuilder;
+import org.apache.http.message.BasicNameValuePair;
+import org.apache.http.client.entity.UrlEncodedFormEntity;
+
 import java.io.InputStream;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -229,6 +235,120 @@ public class BodyApi {
     }
     return localVarRequestBuilder;
   }
+  /**
+   * Test array of binary in multipart mime
+   * Test array of binary in multipart mime
+   * @param files  (required)
+   * @return String
+   * @throws ApiException if fails to make API call
+   */
+  public String testBodyMultipartFormdataArrayOfBinary(List<File> files) throws ApiException {
+    ApiResponse<String> localVarResponse = testBodyMultipartFormdataArrayOfBinaryWithHttpInfo(files);
+    return localVarResponse.getData();
+  }
+
+  /**
+   * Test array of binary in multipart mime
+   * Test array of binary in multipart mime
+   * @param files  (required)
+   * @return ApiResponse&lt;String&gt;
+   * @throws ApiException if fails to make API call
+   */
+  public ApiResponse<String> testBodyMultipartFormdataArrayOfBinaryWithHttpInfo(List<File> files) throws ApiException {
+    HttpRequest.Builder localVarRequestBuilder = testBodyMultipartFormdataArrayOfBinaryRequestBuilder(files);
+    try {
+      HttpResponse<InputStream> localVarResponse = memberVarHttpClient.send(
+          localVarRequestBuilder.build(),
+          HttpResponse.BodyHandlers.ofInputStream());
+      if (memberVarResponseInterceptor != null) {
+        memberVarResponseInterceptor.accept(localVarResponse);
+      }
+      try {
+        if (localVarResponse.statusCode()/ 100 != 2) {
+          throw getApiException("testBodyMultipartFormdataArrayOfBinary", localVarResponse);
+        }
+        // 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");
+          String responseBodyText = s.hasNext() ? s.next() : "";
+          return new ApiResponse<String>(
+                  localVarResponse.statusCode(),
+                  localVarResponse.headers().map(),
+                  responseBodyText
+          );
+        } else {
+            throw new RuntimeException("Error! The response Content-Type is supposed to be `text/plain` but it's not: " + localVarResponse);
+        }
+      } finally {
+      }
+    } catch (IOException e) {
+      throw new ApiException(e);
+    }
+    catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
+      throw new ApiException(e);
+    }
+  }
+
+  private HttpRequest.Builder testBodyMultipartFormdataArrayOfBinaryRequestBuilder(List<File> files) throws ApiException {
+    // verify the required parameter 'files' is set
+    if (files == null) {
+      throw new ApiException(400, "Missing the required parameter 'files' when calling testBodyMultipartFormdataArrayOfBinary");
+    }
+
+    HttpRequest.Builder localVarRequestBuilder = HttpRequest.newBuilder();
+
+    String localVarPath = "/body/application/octetstream/array_of_binary";
+
+    localVarRequestBuilder.uri(URI.create(memberVarBaseUri + localVarPath));
+
+    localVarRequestBuilder.header("Accept", "text/plain");
+
+    MultipartEntityBuilder multiPartBuilder = MultipartEntityBuilder.create();
+    boolean hasFiles = false;
+    for (int i=0; i < files.size(); i++) {
+        multiPartBuilder.addBinaryBody("files", files.get(i));
+        hasFiles = true;
+    }
+    HttpEntity entity = multiPartBuilder.build();
+    HttpRequest.BodyPublisher formDataPublisher;
+    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();
+        formDataPublisher = HttpRequest.BodyPublishers.ofInputStream(() -> Channels.newInputStream(pipe.source()));
+    } else {
+        ByteArrayOutputStream formOutputStream = new ByteArrayOutputStream();
+        try {
+            entity.writeTo(formOutputStream);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+        formDataPublisher = HttpRequest.BodyPublishers
+            .ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray()));
+    }
+    localVarRequestBuilder
+        .header("Content-Type", entity.getContentType().getValue())
+        .method("POST", formDataPublisher);
+    if (memberVarReadTimeout != null) {
+      localVarRequestBuilder.timeout(memberVarReadTimeout);
+    }
+    if (memberVarInterceptor != null) {
+      memberVarInterceptor.accept(localVarRequestBuilder);
+    }
+    return localVarRequestBuilder;
+  }
   /**
    * Test free form object
    * Test free form object

samples/client/echo_api/java/native/src/test/java/org/openapitools/client/CustomTest.java

@@ -21,7 +21,11 @@ import org.openapitools.client.model.*;
 import org.junit.Test;
 import org.junit.Ignore;
 
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileWriter;
 import java.io.IOException;
+import java.nio.file.Files;
 import java.util.*;
 
 /**
@@ -279,4 +283,33 @@ public class CustomTest {
         Assert.assertEquals("/form/integer/boolean/string", p.path);
         Assert.assertEquals("3b\ninteger_form=1337&boolean_form=true&string_form=Hello+World\n0\n\n", p.body);
     }
+
+    @Test
+    public void testBodyMultipartFormdataArrayOfBinary() throws ApiException {
+        File file1 = Objects.requireNonNull(getFile("Hello"));
+        File file2 = Objects.requireNonNull(getFile("World"));
+
+        String response = bodyApi.testBodyMultipartFormdataArrayOfBinary(List.of(file1, file2));
+        org.openapitools.client.EchoServerResponseParser p = new org.openapitools.client.EchoServerResponseParser(response);
+
+        Assert.assertEquals("/body/application/octetstream/array_of_binary", p.path);
+
+        Assert.assertTrue(p.body.contains(file1.getName()));
+        Assert.assertTrue(p.body.contains("Hello"));
+        Assert.assertTrue(p.body.contains(file2.getName()));
+        Assert.assertTrue(p.body.contains("World"));
+    }
+
+    private File getFile(String content) {
+        try {
+            File tempFile = Files.createTempFile("tempFile", ".txt").toFile();
+            BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
+            writer.write(content);
+            writer.close();
+
+            return tempFile;
+        } catch (IOException e) {
+            return null;
+        }
+    }
 }