code: function (sMethodName, aArgs) {
  				var pCallInstance, sMsrCallInstance = "[sync ] _callInstanceMethod";
  				Measurement.start(sMsrCallInstance, "CM", S_MSR_CAT_CACHE_MANAGER);
  
  				if (this._instance) {
  					Log.debug("Cache Manager: calling instance...");
  					return this._instance[sMethodName].apply(this._instance, aArgs);
  				}
  				Log.debug("Cache Manager: getting instance...");
  
  				pCallInstance = this._getInstance().then(function instanceResolving(instance) {
  					return instance[sMethodName].apply(instance, aArgs);
  				});
  				Measurement.end(sMsrCallInstance);
  
  				return pCallInstance;
  			}
docs: Forwards method's call to the underlying implementation
  @param {string} sMethodName the name of the method to forward
  @param {any[]} aArgs array of arguments
  @returns {Promise}
  @private