code: protected void gitMerge(final String branchName, boolean rebase, boolean noff, boolean ffonly, String message,
              Map<String, String> messageProperties)
              throws MojoFailureException, CommandLineException {
          String sign = "";
          if (gpgSignCommit) {
              sign = "-S";
          }
          String msgParam = "";
          String msg = "";
          if (StringUtils.isNotBlank(message)) {
              msgParam = "-m";
              msg = replaceProperties(message, messageProperties);
          }
          if (rebase) {
              getLog().info("Rebasing '" + branchName + "' branch.");
              executeGitCommand("rebase", sign, branchName);
          } else if (ffonly) {
              getLog().info("Merging (--ff-only) '" + branchName + "' branch.");
              executeGitCommand("merge", "--ff-only", sign, branchName);
          } else if (noff) {
              getLog().info("Merging (--no-ff) '" + branchName + "' branch.");
              executeGitCommand("merge", "--no-ff", sign, branchName, msgParam, msg);
          } else {
              getLog().info("Merging '" + branchName + "' branch.");
              executeGitCommand("merge", sign, branchName, msgParam, msg);
          }
      }
docs: Executes git rebase or git merge --ff-only or git merge --no-ff or git merge.
  
  @param branchName
  Branch name to merge.
  @param rebase
  Do rebase.
  @param noff
  Merge with --no-ff.
  @param ffonly
  Merge with --ff-only.
  @param message
  Merge commit message.
  @param messageProperties
  Properties to replace in message.
  @throws MojoFailureException
  @throws CommandLineException