code: public ItemRequest<CustomField> findById(String customField) {
      
          String path = String.format("/custom_fields/%s", customField);
          return new ItemRequest<CustomField>(this, CustomField.class, path, "GET");
      }
docs: Returns the complete definition of a custom field's metadata.
  
  @param  customField Globally unique identifier for the custom field.
  @return Request object