B10 (and B7)'s problem data is simply too big to load into memory (solving it just takes 10-20% more memory and isn't a problem).

It goes OoM at

at org.optaplanner.examples.machinereassignment.persistence.MachineReassignmentImporter$MachineReassignmentInputBuilder.readMachineList(MachineReassignmentImporter.java)

The problem is this field:

public class MrMachine ... {
    ...
    private Map<MrMachine, Integer> machineMoveCostMap; // key is toMachine
}

For 10000 machines that's just too much data.

We see 3 solutions:
1) remove B7 and B10 from the tests
2) increase the heap space on the test environments (=jenkins, local machines, etc)
3) use a more memory friendly Map.