Map<AnyObjectId, Set<Ref>> allsRefs = git.getRepository().getAllRefsByPeeledObjectId();
    Iterable<RevCommit> commits = git.log().call();
    for (RevCommit commit : commits) {
      log.info("commit msg={}", commit.getShortMessage());
      Set<Ref> commitRefs = allsRefs.get(commit);
      if (commitRefs == null)
        continue;
      for (Ref ref : commitRefs) {
        String name = ref.getName();
        log.info("    rev={}", name);
      }
    }

/**
	 * Returns the commits returned by the <code>git log --merges</code> command call.
	 * Commits with 2 or more parents are considered merges, as says the 'git-log' mannual .
	 * 
	 * @return
	 */
	public List<RevCommit> call() {
		ArrayList<RevCommit> commits = new ArrayList<RevCommit>();
		
		try {
			git = new Git(repository);
			
			Iterable<RevCommit> logs = git.log().all().call();
			for (RevCommit aCommit : logs) {
				count++;
				if (aCommit.getParentCount() >= 2) {
					commits.add(aCommit);
				}else continue;
			}	
		} catch (GitAPIException e) {
			// TODO treat GitAPIException
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
        
		return commits;
	}

git push ssh://username@git.eclipse.org:29418/jgit/jgit.git HEAD:origin/master

$ find .git/refs

$ git push ssh://username@git.eclipse.org:29418/jgit/jgit.git HEAD:refs/heads/master
$ git push ssh://username@git.eclipse.org:29418/jgit/jgit.git HEAD:heads/master