code: function(sPropertyName) {
  			var oProperty = this._oPropertySet[sPropertyName];
  			if (oProperty == null) {
  				throw "no such property with name " + sPropertyName;
  			}
  
  			if (oProperty.extensions != undefined) {
  				for (var i = -1, oExtension; (oExtension = oProperty.extensions[++i]) !== undefined;) {
  					if (oExtension.name == "text") {
  						return this.findPropertyByName(oExtension.value);
  					}
  				}
  			}
  			return null;
  		}
docs: Get the text property related to the property with specified name
  (identified by property metadata annotation sap:text)
  
  @param {string}
  sPropertyName Property name
  @returns {object} The datajs object representing the text property or
  null if it does not exist
  @public
  @function
  @name sap.ui.model.analytics.odata4analytics.EntityType#getTextPropertyOfProperty