public CredentialRetriever dockerConfig() {
    return dockerConfig(
        DockerConfigCredentialRetriever.create(
            imageReference.getRegistry(),
            Paths.get(System.getProperty("user.home"), ".docker", "config.json")));
  }
Creates a new {@link CredentialRetriever} that tries to retrieve credentials from Docker config
(located at {@code System.getProperty("user.home")/.docker/config.json}).

@return a new {@link CredentialRetriever}
@see DockerConfigCredentialRetriever
jib-core/src/main/java/com/google/cloud/tools/jib/frontend/CredentialRetrieverFactory.java