code: def get_output_jsonpath(self, sub_output=None):
          
          output_jsonpath_field = self.get_output_jsonpath_field(sub_output)
  
          metadata = self.extractor.get_metadata()
          metadata['source'] = str(self.input_fields)
          extractor_filter = ""
          is_first = True
          for key, value in metadata.iteritems():
              if is_first:
                  is_first = False
              else:
                  extractor_filter = extractor_filter + " & "
  
              if isinstance(value, basestring):
                  extractor_filter = extractor_filter\
                      + "{}=\"{}\"".format(key,
                                           re.sub('(?<=[^\\\])\"', "'", value))
              elif isinstance(value, types.ListType):
                  extractor_filter = extractor_filter\
                      + "{}={}".format(key, str(value))
          output_jsonpath = "{}[?{}].result.value".format(
              output_jsonpath_field, extractor_filter)
  
          return output_jsonpath
docs: Attempt to build a JSONPath filter for this ExtractorProcessor
          that captures how to get at the outputs of the wrapped Extractor