public static String idOf(String entityUuid) {
    requireNonNull(entityUuid, "entityUuid can't be null");
    return ID_PREFIX + entityUuid;
  }
@Test
  public void idOf_returns_argument_with_a_prefix() {
    String s = randomAlphabetic(12);

    assertThat(AuthorizationDoc.idOf(s)).isEqualTo("auth_" + s);
  }