code: public GitlabLabel updateLabel(Serializable projectId,
                                     String name,
                                     String newName,
                                     String newColor) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + sanitizeProjectId(projectId) + GitlabLabel.URL;
          GitlabHTTPRequestor requestor = retrieve().method(PUT);
          requestor.with("name", name);
          if (newName != null) {
              requestor.with("new_name", newName);
          }
          if (newColor != null) {
              requestor = requestor.with("color", newColor);
          }
          return requestor.to(tailUrl, GitlabLabel.class);
      }
docs: Updates an existing label.
  
  @param projectId The ID of the project containing the label.
  @param name      The name of the label to update.
  @param newName   The updated name.
  @param newColor  The updated color.
  @return The updated, deserialized label.
  @throws IOException on gitlab api call error