public static ConnectionGroup getOrCreateConnectionGroup(String namespace) {
        AssertUtil.assertNotBlank(namespace, "namespace should not be empty");
        ConnectionGroup group = getOrCreateGroup(namespace);
        return group;
    }
@Test
    public void testGetOrCreateConnectionGroup() {
        String namespace = "test-namespace";
        assertNull(ConnectionManager.getConnectionGroup(namespace));
        ConnectionGroup group1 = ConnectionManager.getOrCreateConnectionGroup(namespace);
        assertNotNull(group1);

        // Put one connection.
        ConnectionManager.addConnection(namespace, "12.23.34.45:1997");
        ConnectionGroup group2 = ConnectionManager.getOrCreateConnectionGroup(namespace);

        assertSame(group1, group2);
    }