I have a maven-wise simple project targeting Java 1.8 here.
mvn javadoc:javadoc
runs fine on OpenJDK 8, but fails on OpenJDK 11 with this error message:
javadoc: error - The code being documented uses modules but the packages defined in https://docs.oracle.com/javase/8/docs/api/ are in the unnamed module.
WTF?!? I'm not doing anything with modules!
I couldn't find anything helpful on the web, even though I'd assume this to be a quite common problem. Maybe it's just because most people still stick to Java 8.