code: protected void closeCallUnauthenticated(final ServerCall<?, ?> call, final AuthenticationException aex) {
          call.close(Status.UNAUTHENTICATED.withCause(aex).withDescription(UNAUTHENTICATED_DESCRIPTION), new Metadata());
      }
docs: Close the call with {@link Status#UNAUTHENTICATED}.
  
  @param call The call to close.
  @param aex The exception that was the cause.