@Test
public void pairWithRightNullAreEqual() {

    Pair<Command, Command> pair1 = new Pair<Command, Command>(Command.HasData, null);
    Pair<Command, Command> pair2 = new Pair<Command, Command>(Command.HasData, null);
    assertEquals(pair1, pair2);
    assertEquals(pair1.hashCode(), pair2.hashCode());
}