public static void checkNullOrNotEmpty(@Nullable String value, String propertyName) {
    if (value == null) {
      // pass
      return;
    }
    Preconditions.checkArgument(
        !value.trim().isEmpty(), "Property '" + propertyName + "' cannot be an empty string");
  }
@Test
  public void testCheckNullOrNotEmpty_valuePass() {
    Validator.checkNullOrNotEmpty("value", "test");
  }