Add support for the parameter type corresponding to headerMapIndex for user object (#1581)

* feat: add support for the parameter type corresponding to headerMapIndex for user object

* feat: add a resolution of the user pojo object

* feat: add a resolution of the user pojo object

Co-authored-by: Marvin Froeder <velo@users.noreply.github.com>

Author: mroccyen

core/src/main/java/feign/Contract.java

@@ -156,10 +156,10 @@ protected MethodMetadata parseAndValidateMetadata(Class<?> targetType, Method me
       }
 
       if (data.headerMapIndex() != null) {
-        checkMapString(
-            "HeaderMap",
-            parameterTypes[data.headerMapIndex()],
-            genericParameterTypes[data.headerMapIndex()]);
+        // check header map parameter for map type
+        if (Map.class.isAssignableFrom(parameterTypes[data.headerMapIndex()])) {
+          checkMapKeys("HeaderMap", genericParameterTypes[data.headerMapIndex()]);
+        }
       }
 
       if (data.queryMapIndex() != null) {

core/src/main/java/feign/ReflectiveFeign.java

@@ -248,8 +248,10 @@ public RequestTemplate create(Object[] argv) {
       }
 
       if (metadata.headerMapIndex() != null) {
-        template =
-            addHeaderMapHeaders((Map<String, Object>) argv[metadata.headerMapIndex()], template);
+        // add header map parameters for a resolution of the user pojo object
+        Object value = argv[metadata.headerMapIndex()];
+        Map<String, Object> headerMap = toQueryMap(value);
+        template = addHeaderMapHeaders(headerMap, template);
       }
 
       return template;

core/src/test/java/feign/DefaultContractTest.java

@@ -423,6 +423,14 @@ public void headerMapSubclass() throws Exception {
     assertThat(md.headerMapIndex()).isEqualTo(0);
   }
 
+  @Test
+  public void headerMapUserObject() throws Exception {
+    final MethodMetadata md =
+        parseAndValidateMetadata(
+            HeaderMapInterface.class, "headerMapUserObject", HeaderMapUserObject.class);
+    assertThat(md.headerMapIndex()).isEqualTo(0);
+  }
+
   interface Methods {
 
     @RequestLine("POST /")
@@ -522,7 +530,8 @@ Response recordsByNameAndType(
   interface AutoDiscoverParamNames {
 
     @RequestLine("GET /domains/{domainId}/records?name={name}&type={type}")
-    Response recordsByNameAndType(@Param int domainId, @Param String name, @Param() String type);
+    Response recordsByNameAndType(
+        @Param("domainId") int domainId, @Param("name") String name, @Param("type") String type);
   }
 
   interface FormParams {
@@ -557,6 +566,33 @@ void multipleHeaderMap(
 
     @RequestLine("POST /")
     void headerMapSubClass(@HeaderMap SubClassHeaders httpHeaders);
+
+    @RequestLine("POST /")
+    void headerMapUserObject(@HeaderMap HeaderMapUserObject httpHeaders);
+  }
+
+  class HeaderMapUserObject {
+    @Param("name1")
+    private String name;
+
+    @Param("grade1")
+    private String grade;
+
+    public String getName() {
+      return name;
+    }
+
+    public void setName(String name) {
+      this.name = name;
+    }
+
+    public String getGrade() {
+      return grade;
+    }
+
+    public void setGrade(String grade) {
+      this.grade = grade;
+    }
   }
 
   interface HeaderParams {

core/src/test/java/feign/FeignTest.java

@@ -251,6 +251,23 @@ public void headerMap() throws Exception {
             entry("Custom-Header", Arrays.asList("fooValue")));
   }
 
+  @Test
+  public void HeaderMapUserObject() throws Exception {
+    server.enqueue(new MockResponse());
+
+    TestInterface api = new TestInterfaceBuilder().target("http://localhost:" + server.getPort());
+
+    HeaderMapUserObject headerMap = new HeaderMapUserObject();
+    headerMap.setName("hello");
+    headerMap.setGrade("5");
+    api.HeaderMapUserObject(headerMap);
+
+    assertThat(server.takeRequest())
+        .hasHeaders(
+            entry("name1", Collections.singletonList("hello")),
+            entry("grade1", Collections.singletonList("5")));
+  }
+
   @Test
   public void headerMapWithHeaderAnnotations() throws Exception {
     server.enqueue(new MockResponse());
@@ -1000,6 +1017,9 @@ void form(
     @RequestLine("GET /")
     void headerMap(@HeaderMap Map<String, Object> headerMap);
 
+    @RequestLine("GET /")
+    void HeaderMapUserObject(@HeaderMap HeaderMapUserObject headerMap);
+
     @RequestLine("GET /")
     @Headers("Content-Encoding: deflate")
     void headerMapWithHeaderAnnotations(@HeaderMap Map<String, Object> headerMap);
@@ -1035,6 +1055,30 @@ public String expand(Object value) {
     }
   }
 
+  class HeaderMapUserObject {
+    @Param("name1")
+    private String name;
+
+    @Param("grade1")
+    private String grade;
+
+    public String getName() {
+      return name;
+    }
+
+    public void setName(String name) {
+      this.name = name;
+    }
+
+    public String getGrade() {
+      return grade;
+    }
+
+    public void setGrade(String grade) {
+      this.grade = grade;
+    }
+  }
+
   class TestInterfaceException extends Exception {
     TestInterfaceException(String message) {
       super(message);