code: private void assertValidDateFieldType(Optional<Field> field) {
  
  		field.ifPresent(it -> {
  
  			if (SUPPORTED_DATE_TYPES.contains(it.getType().getName())) {
  				return;
  			}
  
  			Class<?> type = it.getType();
  
  			if (Jsr310Converters.supports(type)
  					|| ThreeTenBackPortConverters.supports(type)) {
  				return;
  			}
  
  			throw new IllegalStateException(String.format(
  					"Found created/modified date field with type %s but only %s as well as java.time types are supported!",
  					type, SUPPORTED_DATE_TYPES));
  		});
  	}
docs: Checks whether the given field has a type that is a supported date type.
  @param field