We shouldn't start the test matrix if any static checks fails. For this we should have a Check build variant that does the following

./gradlew -PxmlReports.enabled=true --info -x test clean check jar testClasses javadoc

There is no need for MongoDB to be running for this.

Then in run_tests.sh the command for compilation prior to running the tests can be simplified to:

./gradlew --info classes testClasses