code: private User fetch(final String token) {
          try {
              return new DefaultFacebookClient(
                  token,
                  this.requestor,
                  new DefaultJsonMapper(),
                  Version.LATEST
              ).fetchObject(
                  "me", User.class
              );
          } catch (final FacebookException ex) {
              throw new IllegalArgumentException(ex);
          }
      }
docs: Get user name from Facebook, but the code provided.
  @param token Facebook access token
  @return The user found in FB