Creating a new DefaultDockerClient from zero-argument constructor results in NPE

[ljnelson]

The documentation reads in part:

The config instance can be configured via ConfigBuilder or via enviornment [sic] variables (e.g. DOCKER_HOST). In the later [sic] case, you can directly isntantiate [sic] the DefaultDockerClient:

DockerClient client = new DefaultDockerClient();

Related, if I set a DOCKER_HOST environment variable and then do new DefaultDockerClient(new Config()), it fails with a NullPointerException during a call to usesUnixSocket:

java.lang.NullPointerException
at io.fabric8.docker.client.utils.HttpClientUtils.usesUnixSocket(HttpClientUtils.java:197)
at io.fabric8.docker.client.utils.HttpClientUtils.createHttpClient(HttpClientUtils.java:83)
at io.fabric8.docker.client.DefaultDockerClient.<init>(DefaultDockerClient.java:51)