You have a use case in your web application that adds several session-scoped attributes. At the end of theuse case， one of these objects， the manager attribute， is removed and then it needs to decide which of theother session-scoped attributes to remove.
How can this goal be accomplished？（）

You have built a web application that you license to small businesses. The webapp uses a context
parameter， called licenseExtension， which enables certain advanced features based on your client’s licensepackage. When a client pays for a specific service， you provide them with a license extension key that theyinsert into the  of the deployment descriptor. Not every client will have this contextparameter so you need to create a context listener to set up a default value in the licenseExtensionparameter.
Which code snippet will accomplish this goal？（）