Running tests on both parallel and sequence mode using groups and dependsOnGroups attribute

Question

I have a scenario, where in a single class file, i have multiple testcases, in that i want to run few tests in parallel and few in sequence, but sequence tests should execute only after the parallel tests execution completion.

In the testcases , I have used groups and dependsOnGroups, but the parallel tests are running in sequence. Below is my xml file:

test1 and test2 should run first and in parallel, post execution of test1 and test2, test3 and test4 should run in sequence.