assertFalse(system.isRegistered("b"));
MockClassLoaderDomain b = new MockClassLoaderDomain("b");
assertFalse(system.isDomainRegistered(a));
system.registerDomain(a);
system.registerDomain(b);
assertTrue(system.isRegistered("a"));
assertTrue(system.isDomainRegistered(a));
assertTrue(system.isRegistered("b"));
assertTrue(system.isDomainRegistered(b));