Use GitLabApiForm in post requests

Author: jmini

gitlab4j-api/src/main/java/org/gitlab4j/api/RepositoryApi.java

@@ -1167,7 +1167,7 @@ public void generateChangelog(Object projectIdOrPath, String version) throws Git
     public void generateChangelog(Object projectIdOrPath, ChangelogPayload payload) throws GitLabApiException {
         post(
                 Response.Status.OK,
-                payload.getFormData(),
+                new GitLabApiForm(payload.getFormData()),
                 "projects",
                 getProjectIdOrPath(projectIdOrPath),
                 "repository",

gitlab4j-api/src/main/java/org/gitlab4j/api/TopicsApi.java

@@ -113,7 +113,7 @@ public Optional<Topic> getOptionalTopic(Integer id) {
      * @throws GitLabApiException if any exception occurs
      */
     public Topic createTopic(TopicParams params) throws GitLabApiException {
-        Response response = post(Response.Status.CREATED, params.getForm(true), "topics");
+        Response response = post(Response.Status.CREATED, new GitLabApiForm(params.getForm(true)), "topics");
         return (response.readEntity(Topic.class));
     }