public List<GrantedAuthority> getGrantedAuthorities(Collection<String> attributes) {
		ArrayList<GrantedAuthority> gaList = new ArrayList<>();
		for (String attribute : attributes) {
			Collection<GrantedAuthority> c = attributes2grantedAuthoritiesMap
					.get(attribute);
			if (c != null) {
				gaList.addAll(c);
			}
		}
		gaList.trimToSize();

		return gaList;
	}