Obviously not a lawyer, so this isn't legal advice, but my personal interpretation is:
The code is licensed under Apache License, Version 2.0. If you read the Redistribution section:
You may reproduce and distribute copies of the Work or Derivative
Works thereof in any medium, with or without modifications, and in
Source or Object form...
So, yes, you can package it with your jar file. And I would argue that obfuscating the code is modifying it. However, one of the conditions of redistribution is:
If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file...
You need to keep all the notices intact. So don't obfuscate those away :).