I have to respectfully disagree. The docs of just about every java library or framework I've looked at or used have been extensive, detailed and complete.
But are they readable? Relevant? Useful? They're certainly better than nothing, but there's more to good documentation than completeness and detail.
I wonder how much overlap there is between the packages I've used and the ones you've used. I've only been in the Java world for about 3 months, so my perspective is definitely raw and incomplete. Maybe we just have different criteria for what we consider good documentation.
I had successfully avoided Java for most of my career, so it was also an opportunity to learn something new.
That was a terrible mistake. It's almost impossible to find answers that are relevant. There is very little readable documentation, even directly from Oracle. When you do find a relevant bit of information on a forum or blog, it's either outdated or useless because the author doesn't specify what their environment is.
I asked my colleagues for books, blogs or other resources to help me get up to speed. They pretty much laughed and said I'm out of luck.
I won't complain about the tooling. It's bad, but that may be more a matter of taste than anything else.