function observerHandler() {
			// variant switch promise needs to be checked, since there might be a pending on-going variants switch
			// which might result in unnecessary data being stored
			return mPropertyBag.model._oVariantSwitchPromise.then(function() {
				mPropertyBag.model._oHashData.controlPropertyObservers.forEach(function(oObserver) {
					oObserver.destroy();
				});
				// deregister navigation filter if ushell is available
				deRegisterNavigationFilter(mPropertyBag.model);

				// this promise is not returned since the component is getting destroyed,
				// which will also destroy the variant model anyway,
				// but this is just to ensure the model is in sync with the variants state (which is persisted)
				mPropertyBag.model.destroy();
				mPropertyBag.model.oComponentDestroyObserver.unobserve(mPropertyBag.model.oAppComponent, {destroy: true});
				mPropertyBag.model.oComponentDestroyObserver.destroy();
			});
		}
Attaches initial handlers for component lifecycle and persists the loaded variant management.

@param {object} mPropertyBag - Property bag
@param {string} [mPropertyBag.vmReference] - Variant management reference
@param {sap.ui.fl.variants.VariantModel} mPropertyBag.model - Variant model
@param {boolean} [mPropertyBag.updateURL] - Indicating if <code>updateVariantInURL</code> property is enabled for the passed variant management reference

@private
@ui5-restricted sap.ui.fl.variants.VariantModel