code: public static void mapper(final HttpConfig config, final ObjectMapper mapper) {
          mapper(config, mapper, ContentTypes.JSON);
      }
docs: Used to configure the provided Jackson `ObjectMapper` in the configuration context for the default JSON content type.
  
  [source,groovy]
  ----
  def http = HttpBuilder.configure {
  request.uri = "${serverRule.serverUrl}/jackson"
  request.contentType = JSON[0]
  Jackson.mapper(delegate, objectMapper)
  }
  ----
  
  @param config the configuration
  @param mapper the `ObjectMapper` to be used.