The Jenkins git plugin is developed, compiled, and tested with JDK 1.7. The building Jenkins wiki page says that JDK 1.6 is required for Jenkins as a whole, but the git plugin is no longer being checked that it compiles with JDK 1.6, or that it runs with JDK 1.6.
Since April 2015 is the official end of publicly available patches for JDK 1.7, and since Oracle's last publicly available patch for JDK 1.6 was 1.6.0_45 in April 2013, I hope the community sees that as a reasonable approach.
Do you think that JDK 1.6 support is critical for the community of users of the git plugin?
We recently had to refine a change so that users of the git plugin running on Red Hat 5 and Red Hat 6 (git versions prior to 1.7.10) would not be disrupted by the assumption of credentials support in command line git. After that, I included Red Hat 5 and Red Hat 6 machines in my test setup. Maybe we'll need to do something similar here, with some form of conditional for JDK 1.6. If so, then I'll adapt the test automation setup I have to include more testing of JDK 1.6 before new plugin versions are released.