code: function WSTrustRequest(callContext, wstrustEndpointUrl, appliesTo, wstrustEndpointVersion) {
    this._log = new Logger('WSTrustRequest', callContext._logContext);
    this._callContext = callContext;
    this._wstrustEndpointUrl = wstrustEndpointUrl;
    this._appliesTo = appliesTo;
    this._wstrustEndpointVersion = wstrustEndpointVersion;
  }
docs: Creates a new instance of WSTrustRequest
  @constructor
  @private
  @param {object} callContext Contains any context information that applies to the request.
  @param {string}     wstrustEndpointUrl    An STS WS-Trust soap endpoint.
  @param {string}     appliesTo             A URI that identifies a service for which the a token is to be obtained.