public void setOwningUser(String user) {
    Preconditions.checkNotNull(user);
    mOwningUser = user;
  }
@Test
  public void checkEquals() {
    AccessControlList a1 = new AccessControlList();
    a1.setOwningUser("test1");
    DefaultAccessControlList a2 = new DefaultAccessControlList();
    a2.setOwningUser("test2");
    new EqualsTester()
        .addEqualityGroup(new DefaultAccessControlList(), new DefaultAccessControlList())
        .addEqualityGroup(new AccessControlList(), new AccessControlList())
        .addEqualityGroup(a1)
        .addEqualityGroup(a2)
        .testEquals();
  }