code: private void processSimpleField(Field field) {
      PropertyMetadata propertyMetadata = IntrospectionUtils.getPropertyMetadata(field);
      if (propertyMetadata != null) {
        metadata.putPropertyMetadata(propertyMetadata);
      }
    }
docs: Processes the given simple (or primitive) field and updates the metadata.
  
  @param field
  the field to process