code: public GitlabSimpleRepositoryFile updateRepositoryFile(GitlabProject project, String path, String branchName, String commitMsg, String content) throws IOException {
          String tailUrl = GitlabProject.URL + "/" + project.getId() + "/repository/files/" + sanitizePath(path);
          GitlabHTTPRequestor requestor = retrieve().method(PUT);
  
          return requestor
                  .with("branch", branchName)
                  .with("encoding", "base64")
                  .with("commit_message", commitMsg)
                  .with("content", content)
                  .to(tailUrl, GitlabSimpleRepositoryFile.class);
      }
docs: Updates the content of an existing file in the repository
  
  @param project    The Project
  @param path       The file path inside the repository
  @param branchName The name of a repository branch
  @param commitMsg  The commit message
  @param content    The base64 encoded content of the file
  @throws IOException on gitlab api call error