The error happens when you try to load a file using the file manager in Jena 2.10.1, for example
The reason is incorrect initialization of variables in the OWL class. In the following code:
a call to OWL.sameAs will result in a NPE because m_model is null. I guess that if you start with OWL.getURI(), then m_model will be evaluated first and there will be no error, which is why this never occurred before.
I think that a solution would be to make m_model final as well.