A new version of yavijava has been released. This release addresses many issues including a NPE when running parallel operations.
Created PR #71
This should fix an NPE thrown when performing multiple calls concurrently.
Code changed in jenkins
User: Peter Darton
Merge pull request #71 from jordancoll/patch-1
Update yavijava from 6.0.04 to 6.0.05 JENKINS-43962
Code changes merged. Fixed in version 2.16.