    @Test
    public void shouldThrowIllegalArgumentExceptionIfUsernameIsEmptyOrNull() {


        // Given

        Authentication authenticationMock = mock(Authentication.class);
        when(authenticationMock.getPrincipal()).thenReturn("HelloOrg" + Character.LINE_SEPARATOR + "HelloTenant"
                + Character.LINE_SEPARATOR + " ");

        thrown.expect(IllegalArgumentException.class);
        thrown.expectMessage("Authentication principle[HelloOrg" + Character.LINE_SEPARATOR
                + "HelloTenant" + Character.LINE_SEPARATOR + " ] does not contain username.");

        // When
        authTokenBuilder.createAccessToken(authenticationMock);

        // Then
        // Expect test to be passed.
    }