[java][feign] Fix the character escaping in feign generated Content-type and Accept headers in order to generate proper values for these fields (#19895) (#19912)

Author: CaptainAye

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

@@ -47,8 +47,8 @@ public interface {{classname}} extends ApiClient.Api {
 {{/isDeprecated}}
   @RequestLine("{{httpMethod}} {{{path}}}{{#hasQueryParams}}?{{/hasQueryParams}}{{#queryParams}}{{baseName}}={{=<% %>=}}{<%paramName%>}<%={{ }}=%>{{^-last}}&{{/-last}}{{/queryParams}}")
   @Headers({
-{{#vendorExtensions.x-content-type}}    "Content-Type: {{vendorExtensions.x-content-type}}",
-{{/vendorExtensions.x-content-type}}    "Accept: {{#vendorExtensions.x-accepts}}{{.}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
+{{#vendorExtensions.x-content-type}}    "Content-Type: {{{vendorExtensions.x-content-type}}}",
+{{/vendorExtensions.x-content-type}}    "Accept: {{#vendorExtensions.x-accepts}}{{{.}}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
     "{{baseName}}: {{=<% %>=}}{<%paramName%>}<%={{ }}=%>"{{^-last}},
     {{/-last}}{{/headerParams}}
   })
@@ -77,8 +77,8 @@ public interface {{classname}} extends ApiClient.Api {
 {{/isDeprecated}}
   @RequestLine("{{httpMethod}} {{{path}}}{{#hasQueryParams}}?{{/hasQueryParams}}{{#queryParams}}{{baseName}}={{=<% %>=}}{<%paramName%>}<%={{ }}=%>{{^-last}}&{{/-last}}{{/queryParams}}")
   @Headers({
-{{#vendorExtensions.x-content-type}}    "Content-Type: {{vendorExtensions.x-content-type}}",
-{{/vendorExtensions.x-content-type}}    "Accept: {{#vendorExtensions.x-accepts}}{{.}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
+{{#vendorExtensions.x-content-type}}    "Content-Type: {{{vendorExtensions.x-content-type}}}",
+{{/vendorExtensions.x-content-type}}    "Accept: {{#vendorExtensions.x-accepts}}{{{.}}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
     "{{baseName}}: {{=<% %>=}}{<%paramName%>}<%={{ }}=%>"{{^-last}},
     {{/-last}}{{/headerParams}}
   })
@@ -122,8 +122,8 @@ public interface {{classname}} extends ApiClient.Api {
   {{/isDeprecated}}
   @RequestLine("{{httpMethod}} {{{path}}}?{{#queryParams}}{{baseName}}={{=<% %>=}}{<%paramName%>}<%={{ }}=%>{{^-last}}&{{/-last}}{{/queryParams}}")
   @Headers({
-{{#vendorExtensions.x-content-type}}  "Content-Type: {{vendorExtensions.x-content-type}}",
-{{/vendorExtensions.x-content-type}}  "Accept: {{#vendorExtensions.x-accepts}}{{.}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
+{{#vendorExtensions.x-content-type}}  "Content-Type: {{{vendorExtensions.x-content-type}}}",
+{{/vendorExtensions.x-content-type}}  "Accept: {{#vendorExtensions.x-accepts}}{{{.}}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
       "{{baseName}}: {{=<% %>=}}{<%paramName%>}<%={{ }}=%>"{{^-last}},
       {{/-last}}{{/headerParams}}
   })
@@ -162,8 +162,8 @@ public interface {{classname}} extends ApiClient.Api {
   {{/isDeprecated}}
       @RequestLine("{{httpMethod}} {{{path}}}?{{#queryParams}}{{baseName}}={{=<% %>=}}{<%paramName%>}<%={{ }}=%>{{^-last}}&{{/-last}}{{/queryParams}}")
       @Headers({
-  {{#vendorExtensions.x-content-type}}  "Content-Type: {{vendorExtensions.x-content-type}}",
-  {{/vendorExtensions.x-content-type}}  "Accept: {{#vendorExtensions.x-accepts}}{{.}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
+  {{#vendorExtensions.x-content-type}}  "Content-Type: {{{vendorExtensions.x-content-type}}}",
+  {{/vendorExtensions.x-content-type}}  "Accept: {{#vendorExtensions.x-accepts}}{{{.}}}{{^-last}},{{/-last}}{{/vendorExtensions.x-accepts}}",{{#headerParams}}
           "{{baseName}}: {{=<% %>=}}{<%paramName%>}<%={{ }}=%>"{{^-last}},
       {{/-last}}{{/headerParams}}
       })

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

@@ -1273,6 +1273,34 @@ private Optional<CodegenOperation> getByCriteria(List<CodegenOperation> codegenO
             );
     }
 
+    /**
+     * see https://github.com/OpenAPITools/openapi-generator/issues/19895
+     */
+    @Test public void testCharsetInContentTypeCorrectlyEncodedForFeignApi_issue19895() {
+        final Path output = newTempFolder();
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+                .setGeneratorName("java")
+                .setLibrary(FEIGN)
+                .setInputSpec("src/test/resources/3_0/issue_19895.yaml")
+                .setOutputDir(output.toString().replace("\\", "/"));
+
+        final ClientOptInput clientOptInput = configurator.toClientOptInput();
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(clientOptInput).generate();
+
+        validateJavaSourceFiles(files);
+        var defaultApiFile = output.resolve("src/main/java/org/openapitools/client/api/DefaultApi.java");
+        assertThat(files).contains(defaultApiFile.toFile());
+        assertThat(defaultApiFile).content()
+                .doesNotContain(
+                        "Content-Type: application/json;charset&#x3D;utf-8",
+                        "Accept: application/json;charset&#x3D;utf-8")
+                .contains(
+                        "Content-Type: application/json;charset=utf-8",
+                        "Accept: application/json;charset=utf-8"
+                );
+    }
+
     /**
      * See https://github.com/OpenAPITools/openapi-generator/issues/6715
      * <p>

modules/openapi-generator/src/test/resources/3_0/issue_19895.yaml

@@ -0,0 +1,54 @@
+openapi: 3.0.1
+info:
+  title: sample spec
+  description: "Sample spec"
+  version: 0.0.1
+
+paths:
+  /v1/sample:
+    post:
+      operationId: samplePost
+      requestBody:
+        content:
+          application/json;charset=utf-8:
+            schema:
+              properties:
+                name:
+                  type: string
+              type: object
+      responses:
+        200:
+          description: success
+          content:
+            application/json;charset=utf-8:
+              schema:
+                properties:
+                  response:
+                    type: object
+                type: object
+    put:
+      operationId: samplePut
+      parameters:
+        - in: query
+          name: limit
+          schema:
+              type: string
+      requestBody:
+        content:
+          application/json;charset=utf-8:
+            schema:
+              properties:
+                name:
+                  type: string
+              type: object
+      responses:
+        200:
+          description: success
+          content:
+            application/json;charset=utf-8:
+              schema:
+                properties:
+                  response:
+                    type: object
+                type: object
+