@Override
    public V remove(Object key) {
        // will throw UnsupportedOperationException; delegate anyway for testability
        return underlying().remove(key);
    }
@Test
    public void testDelegationOfUnsupportedFunctionRemoveByKey() {
        new PCollectionsHashMapWrapperDelegationChecker<>()
            .defineMockConfigurationForUnsupportedFunction(mock -> mock.remove(eq(this)))
            .defineWrapperUnsupportedFunctionInvocation(wrapper -> wrapper.remove(this))
            .doUnsupportedFunctionDelegationCheck();
    }