Hugo asked for the API documentation,
not a getting started, but I did not realize you needed
documentation on how to include a jar into a Java project. Luckily
Google has information on that.
For the rest, each class has a description on how to use it, like,
for example, agenda. But of course you knew that, because you read
our documentation before voicing an opinion.
Is the the perfect amount of documentation? No. There can always
be more, it is a matter of choosing where to spent one's free time
on. ControlsFX, which you kindly swipe under the same rug as
JFXtras, has invested a lot of energy in their documentation,
including a "getting started" which you apparently need so much.
But you of course know this already, because you read that before
voicing an opinion.
But, out of pure curiosity... What is your open source
contribution to the world?