function executeAfterSwitch(fnCallback, oModel) {
		// if there are multiple switches triggered very quickly this makes sure that they are being executed one after another
		oModel._oVariantSwitchPromise = oModel._oVariantSwitchPromise
		.catch(function() {})
		.then(fnCallback);
		VariantManagementState.setVariantSwitchPromise(oModel.sFlexReference, oModel._oVariantSwitchPromise);
		return oModel._oVariantSwitchPromise;
	}
Adds the passed function to the variant switch promise and returns the whole promise chain.

@param {function():Promise} fnCallback - Callback function returning a promise
@param {sap.ui.fl.variants.VariantModel} oModel - Variant model
@param {string} sVMReference - Variant Management reference
@returns {Promise<undefined>} Resolves when the variant model is not busy anymore
@private