[Java][client] Fix feign classcastexception when getting headers (#16745)

* Avoid ClassCastException when getting headers (the header values are Collection<String> and not List<String>)
Delete unused classes

* Remove feign10x

* Add unit test
Refactor to avoid creating the headers map when ApiResponse is not used

.gitignore

@@ -49,8 +49,6 @@ nb-configuration.xml
 /target
 /generated-files
 test-output/
-nbactions.xml
-test-output/
 
 # website
 website/build/
@@ -73,7 +71,6 @@ samples/client/petstore/build
 samples/client/petstore/cpp-qt/PetStore/moc_*
 samples/client/petstore/cpp-qt/PetStore/*.o
 samples/client/petstore/cpp-qt/build-*
-samples/client/petstore/cpp-qt/build-*
 samples/client/petstore/cpp-qt/PetStore/PetStore
 samples/client/petstore/cpp-qt/PetStore/Makefile
 samples/client/petstore/cpp-qt/PetStore/PetStore.pro.user
@@ -100,9 +97,7 @@ samples/client/petstore/java/jersey2/build/
 samples/client/petstore/java/okhttp-gson/.gradle/
 samples/client/petstore/java/okhttp-gson/build/
 samples/client/petstore/java/feign/build/
-samples/client/petstore/java/feign10x/build/
 samples/client/petstore/java/feign/project/
-samples/client/petstore/java/feign10x/project/
 samples/client/petstore/java/retrofit/build/
 samples/client/petstore/java/retrofit2/build/
 samples/client/petstore/java/retrofit2/hello.txt
@@ -110,7 +105,6 @@ samples/client/petstore/java/retrofit2rx/build/
 samples/client/petstore/java/default/build/
 samples/client/petstore/scala/build/
 samples/client/petstore/java/resttemplate/hello.txt
-samples/client/petstore/java/retrofit2/hello.txt
 samples/client/petstore/java/feign/hello.txt
 samples/client/petstore/java/jersey2-java6/project/
 samples/client/petstore/java/jersey2-java8/project/

modules/openapi-generator/src/main/resources/Java/libraries/feign/ApiResponseDecoder.mustache

@@ -22,14 +22,13 @@ public class ApiResponseDecoder extends JacksonDecoder {
 
     @Override
     public Object decode(Response response, Type type) throws IOException {
-    Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
         //Detects if the type is an instance of the parameterized class ApiResponse
-        Type responseBodyType;
         if (type instanceof ParameterizedType && Types.getRawType(type).isAssignableFrom(ApiResponse.class)) {
             //The ApiResponse class has a single type parameter, the Dto class itself
-            responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
+            Type responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
             Object body = super.decode(response, responseBodyType);
-            return new ApiResponse(response.status(), responseHeaders, body);
+            Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
+            return new ApiResponse<>(response.status(), responseHeaders, body);
         } else {
             //The response is not encapsulated in the ApiResponse, decode the Dto as normal
             return super.decode(response, type);

modules/openapi-generator/src/main/resources/Java/libraries/feign/model/ApiResponse.mustache

@@ -1,19 +1,19 @@
 package {{modelPackage}};
 
 import java.util.Map;
-import java.util.List;
+import java.util.Collection;
 
 public class ApiResponse<T>{
 
     final private int statusCode;
-    final private Map<String, List<String>> headers;
+    final private Map<String, Collection<String>> headers;
     final private T data;
 
     /**
      * @param statusCode The status code of HTTP response
      * @param headers The headers of HTTP response
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers) {
         this(statusCode, headers, null);
     }
 
@@ -22,7 +22,7 @@ public class ApiResponse<T>{
      * @param headers The headers of HTTP response
      * @param data The object deserialized from response bod
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers, T data) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers, T data) {
         this.statusCode = statusCode;
         this.headers = headers;
         this.data = data;
@@ -32,7 +32,7 @@ public class ApiResponse<T>{
         return statusCode;
     }
 
-    public Map<String, List<String>> getHeaders() {
+    public Map<String, Collection<String>> getHeaders() {
         return headers;
     }
 

samples/client/echo_api/java/feign-gson/src/main/java/org/openapitools/client/model/ApiResponse.java

@@ -1,19 +1,19 @@
 package org.openapitools.client.model;
 
 import java.util.Map;
-import java.util.List;
+import java.util.Collection;
 
 public class ApiResponse<T>{
 
     final private int statusCode;
-    final private Map<String, List<String>> headers;
+    final private Map<String, Collection<String>> headers;
     final private T data;
 
     /**
      * @param statusCode The status code of HTTP response
      * @param headers The headers of HTTP response
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers) {
         this(statusCode, headers, null);
     }
 
@@ -22,7 +22,7 @@ public class ApiResponse<T>{
      * @param headers The headers of HTTP response
      * @param data The object deserialized from response bod
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers, T data) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers, T data) {
         this.statusCode = statusCode;
         this.headers = headers;
         this.data = data;
@@ -32,7 +32,7 @@ public class ApiResponse<T>{
         return statusCode;
     }
 
-    public Map<String, List<String>> getHeaders() {
+    public Map<String, Collection<String>> getHeaders() {
         return headers;
     }
 

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/ApiResponseDecoder.java

@@ -22,14 +22,13 @@ public class ApiResponseDecoder extends JacksonDecoder {
 
     @Override
     public Object decode(Response response, Type type) throws IOException {
-    Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
         //Detects if the type is an instance of the parameterized class ApiResponse
-        Type responseBodyType;
         if (type instanceof ParameterizedType && Types.getRawType(type).isAssignableFrom(ApiResponse.class)) {
             //The ApiResponse class has a single type parameter, the Dto class itself
-            responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
+            Type responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
             Object body = super.decode(response, responseBodyType);
-            return new ApiResponse(response.status(), responseHeaders, body);
+            Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
+            return new ApiResponse<>(response.status(), responseHeaders, body);
         } else {
             //The response is not encapsulated in the ApiResponse, decode the Dto as normal
             return super.decode(response, type);

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/JacksonResponseDecoder.java

@@ -1,38 +0,0 @@
-package org.openapitools.client;
-
-import com.fasterxml.jackson.databind.ObjectMapper;
-import feign.Response;
-import feign.Types;
-import feign.jackson.JacksonDecoder;
-
-import java.io.IOException;
-import java.lang.reflect.ParameterizedType;
-import java.lang.reflect.Type;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Map;
-
-import org.openapitools.client.model.HttpResponse;
-
-public class JacksonResponseDecoder extends JacksonDecoder {
-
-    public JacksonResponseDecoder(ObjectMapper mapper) {
-        super(mapper);
-    }
-
-    @Override
-    public Object decode(Response response, Type type) throws IOException {
-    Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
-        //Detects if the type is an instance of the parameterized class HttpResponse
-        Type responseBodyType;
-        if (Types.getRawType(type).isAssignableFrom(HttpResponse.class)) {
-            //The HttpResponse class has a single type parameter, the Dto class itself
-            responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
-            Object body = super.decode(response, responseBodyType);
-            return new HttpResponse(responseHeaders, body, response.status());
-        } else {
-            //The response is not encapsulated in the HttpResponse, decode the Dto as normal
-            return super.decode(response, type);
-        }
-    }
-}

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/ApiResponse.java

@@ -1,19 +1,19 @@
 package org.openapitools.client.model;
 
 import java.util.Map;
-import java.util.List;
+import java.util.Collection;
 
 public class ApiResponse<T>{
 
     final private int statusCode;
-    final private Map<String, List<String>> headers;
+    final private Map<String, Collection<String>> headers;
     final private T data;
 
     /**
      * @param statusCode The status code of HTTP response
      * @param headers The headers of HTTP response
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers) {
         this(statusCode, headers, null);
     }
 
@@ -22,7 +22,7 @@ public class ApiResponse<T>{
      * @param headers The headers of HTTP response
      * @param data The object deserialized from response bod
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers, T data) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers, T data) {
         this.statusCode = statusCode;
         this.headers = headers;
         this.data = data;
@@ -32,7 +32,7 @@ public class ApiResponse<T>{
         return statusCode;
     }
 
-    public Map<String, List<String>> getHeaders() {
+    public Map<String, Collection<String>> getHeaders() {
         return headers;
     }
 

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/model/HttpResponse.java

@@ -1,31 +0,0 @@
-package org.openapitools.client.model;
-
-import java.util.Map;
-import java.util.Collection;
-
-public class HttpResponse<T>{
-
-  private Map<String, Collection<String>> headers;
-
-  private T body;
-
-  private int status;
-
-  public HttpResponse(Map<String, Collection<String>> headers, T body, int status) {
-    this.headers = headers;
-    this.body = body;
-    this.status = status;
-  }
-
-  public T getBody(){
-    return body;
-  }
-
-  public Map<String, Collection<String>> getHeaders(){
-    return headers;
-  }
-
-  public int getStatus(){
-    return status;
-  }
-}

samples/client/petstore/java/feign/src/main/java/org/openapitools/client/ApiResponseDecoder.java

@@ -22,14 +22,13 @@ public class ApiResponseDecoder extends JacksonDecoder {
 
     @Override
     public Object decode(Response response, Type type) throws IOException {
-    Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
         //Detects if the type is an instance of the parameterized class ApiResponse
-        Type responseBodyType;
         if (type instanceof ParameterizedType && Types.getRawType(type).isAssignableFrom(ApiResponse.class)) {
             //The ApiResponse class has a single type parameter, the Dto class itself
-            responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
+            Type responseBodyType = ((ParameterizedType) type).getActualTypeArguments()[0];
             Object body = super.decode(response, responseBodyType);
-            return new ApiResponse(response.status(), responseHeaders, body);
+            Map<String, Collection<String>> responseHeaders = Collections.unmodifiableMap(response.headers());
+            return new ApiResponse<>(response.status(), responseHeaders, body);
         } else {
             //The response is not encapsulated in the ApiResponse, decode the Dto as normal
             return super.decode(response, type);

samples/client/petstore/java/feign/src/main/java/org/openapitools/client/model/ApiResponse.java

@@ -1,19 +1,19 @@
 package org.openapitools.client.model;
 
 import java.util.Map;
-import java.util.List;
+import java.util.Collection;
 
 public class ApiResponse<T>{
 
     final private int statusCode;
-    final private Map<String, List<String>> headers;
+    final private Map<String, Collection<String>> headers;
     final private T data;
 
     /**
      * @param statusCode The status code of HTTP response
      * @param headers The headers of HTTP response
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers) {
         this(statusCode, headers, null);
     }
 
@@ -22,7 +22,7 @@ public class ApiResponse<T>{
      * @param headers The headers of HTTP response
      * @param data The object deserialized from response bod
      */
-    public ApiResponse(int statusCode, Map<String, List<String>> headers, T data) {
+    public ApiResponse(int statusCode, Map<String, Collection<String>> headers, T data) {
         this.statusCode = statusCode;
         this.headers = headers;
         this.data = data;
@@ -32,7 +32,7 @@ public class ApiResponse<T>{
         return statusCode;
     }
 
-    public Map<String, List<String>> getHeaders() {
+    public Map<String, Collection<String>> getHeaders() {
         return headers;
     }
 

samples/client/petstore/java/feign/src/test/java/org/openapitools/client/ApiResponseDecoderTest.java

@@ -0,0 +1,60 @@
+package org.openapitools.client;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableMap;
+import feign.Request;
+import feign.Request.HttpMethod;
+import feign.RequestTemplate;
+import feign.Response;
+import java.io.IOException;
+import java.util.Collection;
+import java.util.Collections;
+import org.junit.jupiter.api.Test;
+import org.openapitools.client.model.ApiResponse;
+import org.openapitools.client.model.Cat;
+
+class ApiResponseDecoderTest {
+
+  private final ObjectMapper objectMapper = new ObjectMapper();
+
+  ApiResponseDecoder decoder = new ApiResponseDecoder(objectMapper);
+
+
+  @Test
+  void shouldDecodeApiResponseWithHeaders() throws IOException {
+
+    final Cat cat = makeCat();
+    TypeReference<ApiResponse<Cat>> typeReference = new TypeReference<ApiResponse<Cat>>() {
+    };
+
+    ApiResponse<Cat> response = (ApiResponse<Cat>) decoder.decode(Response.builder()
+        .headers(ImmutableMap.of("Location",
+            Collections.singletonList("https://example.com/cats/1")))
+        .body(objectMapper.writeValueAsBytes(cat))
+        .status(201)
+        .request(buildRequest())
+        .build(), typeReference.getType());
+
+    assertEquals(cat.getColor(), response.getData().getColor());
+    assertEquals(cat.isDeclawed(), response.getData().isDeclawed());
+
+    Collection<String> locationValues = response.getHeaders().get("Location");
+    assertEquals(1, locationValues.size());
+    assertEquals("https://example.com/cats/1", locationValues.iterator().next());
+  }
+
+  private Cat makeCat() {
+    final Cat cat = new Cat();
+    cat.color("black");
+    cat.declawed(true);
+    return cat;
+  }
+
+  private Request buildRequest() {
+    return Request.create(HttpMethod.GET, "https://example.com/cats/1", Collections.emptyMap(),
+        null, new RequestTemplate());
+  }
+}