Improve checking of JSON MIME in Java default and jersey2

to support suffix like charset in "application/json; charset=UTF8"

modules/swagger-codegen/src/main/resources/Java/libraries/jersey2/ApiClient.mustache

@@ -344,6 +344,17 @@ public class ApiClient {
     return params;
   }
 
+  /**
+   * Check if the given MIME is a JSON MIME.
+   * JSON MIME examples:
+   *   application/json
+   *   application/json; charset=UTF8
+   *   APPLICATION/JSON
+   */
+  public boolean isJsonMime(String mime) {
+    return mime != null && mime.matches("(?i)application\\/json(;.*)?");
+  }
+
   /**
    * Select the Accept header's value from the given accepts array:
    *   if JSON exists in the given array, use it;
@@ -354,8 +365,14 @@ public class ApiClient {
    *   null will be returned (not to set the Accept header explicitly).
    */
   public String selectHeaderAccept(String[] accepts) {
-    if (accepts.length == 0) return null;
-    if (StringUtil.containsIgnoreCase(accepts, "application/json")) return "application/json";
+    if (accepts.length == 0) {
+      return null;
+    }
+    for (String accept : accepts) {
+      if (isJsonMime(accept)) {
+        return accept;
+      }
+    }
     return StringUtil.join(accepts, ",");
   }
 
@@ -369,8 +386,14 @@ public class ApiClient {
    *   JSON will be used.
    */
   public String selectHeaderContentType(String[] contentTypes) {
-    if (contentTypes.length == 0) return "application/json";
-    if (StringUtil.containsIgnoreCase(contentTypes, "application/json")) return "application/json";
+    if (contentTypes.length == 0) {
+      return "application/json";
+    }
+    for (String contentType : contentTypes) {
+      if (isJsonMime(contentType)) {
+        return contentType;
+      }
+    }
     return contentTypes[0];
   }
 
@@ -390,7 +413,7 @@ public class ApiClient {
    * Content-Type (only JSON is supported for now).
    */
   public Entity<String> serialize(Object obj, String contentType) throws ApiException {
-    if (contentType.startsWith("application/json")) {
+    if (isJsonMime(contentType)) {
       return Entity.json(json.serialize(obj));
     } else {
       throw new ApiException(400, "can not serialize object into Content-Type: " + contentType);
@@ -414,7 +437,7 @@ public class ApiClient {
     else
       body = "";
 
-    if (contentType.startsWith("application/json")) {
+    if (isJsonMime(contentType)) {
       return json.deserialize(body, returnType);
     } else if (returnType.getType().equals(String.class)) {
       // Expecting string, return the raw response body.