code: def to_cloudformation(self, **kwargs):
          
          resources = []
  
          function = kwargs.get('function')
  
          if not function:
              raise TypeError("Missing required keyword argument: function")
  
          if self.Method is not None:
              # Convert to lower case so that user can specify either GET or get
              self.Method = self.Method.lower()
  
          resources.extend(self._get_permissions(kwargs))
  
          explicit_api = kwargs['explicit_api']
          if explicit_api.get("__MANAGE_SWAGGER"):
              self._add_swagger_integration(explicit_api, function)
  
          return resources
docs: If the Api event source has a RestApi property, then simply return the Lambda Permission resource allowing
          API Gateway to call the function. If no RestApi is provided, then additionally inject the path, method, and the
          x-amazon-apigateway-integration into the Swagger body for a provided implicit API.
  
          :param dict kwargs: a dict containing the implicit RestApi to be modified, should no explicit RestApi \
                  be provided.
          :returns: a list of vanilla CloudFormation Resources, to which this Api event expands
          :rtype: list