lib/Operation.js
function(endpoint, all) {
      if (!_.isNil(endpoint)) {
        all = _.assignIn(
          _.clone(allEndpointParameters(endpoint.parent, endpoint.parameters)),
          all || {})
      }
      return all
    }
function(endpoint, all) {
      if (!_.isNil(endpoint)) {
        all = _.assignIn(
          _.clone(allEndpointParameters(endpoint.parent, endpoint.parameters)),
          all || {})
      }
      return all
    }
First gather all Endpoint parameters, post-order walk