I have solved the XPAL bounce problem. And the "mode" parameter is now not just obsolete or deprecated is not even accepted anymore. The mode is being cared of internally. To adjust the bounciness, all you need is to set a value for the "bounce" surface parameter.
Currently a JOODE bug leads to an ArrayIndexOutOfBoundsException, if "bounce" is used and "mu" is non-zero. There for I have defaulted "mu" to 10f (what ever "mu" is good for). If you have manually set it to 0f, you will face this AIOOBE.
I have additionally added setEnabled()/isEnabled() methods to Body and Collideable.
Enjoy

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Marvin