@Override
	public Collection<? extends GrantedAuthority> getAuthorities() {
		
		Set<String> roles = this.getRoles();

		if (roles == null) {
			return Collections.emptyList();
		}

		Set<GrantedAuthority> authorities = new HashSet<GrantedAuthority>();
		for (String role : roles) {
			authorities.add(new SimpleGrantedAuthority(role));
		}
		return authorities;
	}