In order to catch Javadoc errors in the build, we now enable the
`Xwerror` flag for the `javadoc` tool. In addition, we now use
`Xdoclint:syntax` instead of `Xdoclint:none` in order to validate
syntax within our Javadoc.
This commit fixes all resulting Javadoc errors and warnings.
This commit also upgrades to Undertow 2.2.12.Final and fixes the
artifact names for exclusions for the Servlet and annotations APIs.
The incorrect exclusion of the Servlet API resulted in the Servlet API
being on the classpath twice for the javadoc task, which resulted in the
following warnings in previous builds.
javadoc: warning - Multiple sources of package comments found for package "javax.servlet"
javadoc: warning - Multiple sources of package comments found for package "javax.servlet.http"
javadoc: warning - Multiple sources of package comments found for package "javax.servlet.descriptor"
javadoc: warning - Multiple sources of package comments found for package "javax.servlet.annotation"
Closes gh-27480