public static String idOf(String entityUuid) {
    requireNonNull(entityUuid, "entityUuid can't be null");
    return ID_PREFIX + entityUuid;
  }
@Test
  public void idOf_fails_with_NPE_if_argument_is_null() {
    assertThatThrownBy(() -> AuthorizationDoc.idOf(null))
      .isInstanceOf(NullPointerException.class)
      .hasMessage("entityUuid can't be null");
  }