Cannot suppress incubating warning

### New feature, improvement proposal

When I want to build javadoc for a module that links incubating module (like vector API) there is no way to suppress this warning in the `javadoc` itself, which also means that I can't use `maven-javadoc-plugin` with `failOnWarnings`. As a stop-gap solution, before it is possible to suppress this in the javadoc, are you willing to accept this as an opt-in feature? (filter out incubating warnings if this feature is enabled)

Start by reviewing how the maven-javadoc-plugin collects and reports javadoc warnings, focusing on the path used with failOnWarnings. Determine whether incubating warnings can be identified reliably and define the opt-in behavior requested in the issue. Done means the opt-in filter suppresses only those warnings while other warnings still trigger failOnWarnings.

Written by the indexing model from the issue text.