SXP fails staging validation checker

We have policies setup in Nexus that requires all staging repo artifacts to pass a series of validation checks before allowing them to be released. The following needs to be fixed, since the Nexus repos are failing to close when the repos are created through the maven stage jobs:

• POM validation
• Source validation
• Javadocs validation
• Reactivate the validation checker

We've temporarily disabled the validation checker for the SXP project but it really needs to be enabled. We need to resolve the checkers ideally.