Hey Joe,
This forum is not meant for specific-issue technical support, but for high level discussion of the platform and services, design patterns, behaviours, etc. This issue should have been posted to
Stack Overflow, where there is a large community of helpful users. We monitor Stack Overflow as well, so you can also rest assured we are likely to see your post. Now, as to this specific issue, it seems clear from the error message that the version of Java on your system is 6, while
7 is what's required to compile and deploy in production, since as mentioned in the docs, the App Engine Java Standard Runtime is using Java 7.
So, you can check by running "java -version" at the command line, and if you don't see something like "
java version "1.7.0_80"", you'll know to install Java 7 to proceed, which should take care of the error.
Cheers,
Nick
Cloud Platform Community Support