@Deprecated
    public static DockerCmdExecFactory getDefaultDockerCmdExecFactory() {
        return new JerseyDockerCmdExecFactory();
    }
@Test
    public void testConcurrentClientBuilding() throws Exception {
        // we use it to check instance uniqueness
        final Set<DockerCmdExecFactory> instances = Collections.synchronizedSet(new HashSet<>());

        Runnable runnable = () -> {
            DockerCmdExecFactory factory = DockerClientBuilder.getDefaultDockerCmdExecFactory();
            // factory created
            assertNotNull(factory);
            // and is unique
            assertFalse(instances.contains(factory));
            instances.add(factory);
        };

        parallel(AMOUNT, runnable);
        // set contains all required unique instances
        assertEquals(AMOUNT, instances.size());
    }