Is there documentation for feature gneration?

I could not find any documentation about how to use the feature generation while training a model for the name finder.  Nor could I find any information about how to train a Maxent or Perceptron model, or how to configure these algorithms. 

I am aware of the basic documentation here http://opennlp.apache.org/docs/1.9.0/manual/opennlp.html  but it does not help beyond getting started.

seems other people cannot find any as well

https://stackoverflow.com/questions/11989633/custom-feature-generation-in-opennlp-namefinder-api

So basically you have put all this work into creating this software but not included sufficient documentation or example how to configure and use it, which basically renders it useless to us if we cannot figure it out.

Is there another location where I can find further documentation or examples? If not are there any plans to address this?