Currently the UnitTestSupport only sets additional properties (extracted from the POM). It should also use the same Maven Execution JRE as being used by Maven Launches (determined from maven-enforcer-plugin, requireJavaVersion rule).
Otherwise the project execution environment JRE is used which is often not suitable as often tests run with a newer version than the bytecode version which is generated (called project execution environment).

Unfortunately JDT does not natively support the two different versions (build for vs. build with), therefore when these versions differ one needs to manually modify all test configurations.