The generate-javadoc job in the 'Release' GH Actions workflow is failing. This is because the default behaviour of the maven-javadoc-plugin (updated in #239) has changed.

When the javadoc:javadoc goal is used, it no longer aggregates the Javadoc for a project at root level by default, it instead generates a separate Javadoc for each module (since version 3.1.0). This creates directories in a different location and causes the job to fail. This can be fixed by using the javadoc:aggregate goal instead.

In addition, the Javadocs created do not have the navigation frame on the left hand side. This is caused by a change to the Javadoc tool which disables this by default in Java 11. When enabled, the frames are not automatically shown (since Java 9). In Java 13 and newer they have been removed completely. In future (post Java 11), there have been some community efforts to restore the navigation frame, or an alternative documentation framework could be used instead of Javadoc.