Is there a way to validate setup.xml fields?

I am in the process of developing a Splunk app that I would like to eventually release on Splunkbase. In my app I need user credentials to pull data from. I have created a custom endpoint, handler, and setup.xml file to get the user credentials during the setup process. I would like to validate that the credentials are correct and can be used to authenticate with a script, but cannot find any documentation on validating fields. Is there any way to perform validation like this?