code: function (oEvent) {
  			// open field ext ui
  			var oUshellContainer = FlUtils.getUshellContainer();
  			var oCrossAppNav = oUshellContainer.getService("CrossApplicationNavigation");
  			var sHrefForFieldExtensionUi = (oCrossAppNav && oCrossAppNav.hrefForExternal({
  				target : {
  					semanticObject : "CustomField",
  					action : "develop"
  				},
  				params : {
  					businessContexts : this._oCurrentFieldExtInfo.BusinessContexts.map( function( oBusinessContext){
  						return oBusinessContext.BusinessContext;
  					}),
  					serviceName : this._oCurrentFieldExtInfo.ServiceName,
  					serviceVersion : this._oCurrentFieldExtInfo.ServiceVersion,
  					entityType : this._oCurrentFieldExtInfo.EntityType
  				}
  			}));
  			Utils.openNewWindow(sHrefForFieldExtensionUi);
  		}
docs: Function called when custom field button was pressed
  
  @param {sap.ui.base.Event}
  oEvent event object