NPE in maven-javadoc-plugin 3.0.0 in Java 11

Fixed in commit ec93e0a3c8d321b0d60a5898ed9b2770b0115320

Note that this is far from perfect (see https://shibboleth.atlassian.net/browse/JPAR-129#icft=JPAR-129) but it moves the ball forward.

The status after this commit is that:

• Everything works as before when building with Java 8.

• Things look plausible when building with Java except that Java SE APIs and Java EE APIs are not recognised, and appear as plain text rather than hyperlinks.

• Other weirdness happens under both Java 9 and Java 10 but we don't care. Don't do that.

maven-javadoc-plugin 3.0.2 has now become 3.1.0, which I guess means it now has functional additions as well as bug fixes (although I don't think they hew strictly to semantic versioning).

Still unreleased, although all issues slated for it have now been completed.

Response is that "we simply cannot fix issues or do releases on demand, so please be patient" along with a suggestion that I use the workround.

I will try and find a way of moving forward that doesn't make solving https://shibboleth.atlassian.net/browse/JPAR-116#icft=JPAR-116 (the malformed URL issue) harder in the long term. My current thought is to define the URLs as properties in the parent POM, then instantiate them in lower-level project POMs so that they can all be changed in one place.

Nice to know that there is some urgency then.

The NPE in 3.0.0 is also the cause of an NPE when mvn site is invoked under Java 11.