code: public Ref renameBranch(Ref branchFrom, String nameTo, boolean forceRename) 
      throws IOException, JavaGitException {
      Ref newBranch = Ref.createBranchRef(nameTo);
      GitBranch gitBranch = new GitBranch();
      gitBranch.renameBranch(path, forceRename, branchFrom, newBranch);
      return newBranch;
    }
docs: Renames a branch
  
  @param branchFrom
  The branch to rename
  @param nameTo
  New branch name
  @param forceRename
  True if force rename option -M should be used.
  False if -m should be used.
  @return new <code>Ref</code> instance
  @throws IOException
  Thrown in case of I/O operation failure
  @throws JavaGitException
  Thrown when there is an error executing git-branch.