private List<DockerConnectionDetector.DockerHostProvider> getDefaultDockerHostProviders(DockerAccessContext dockerAccessContext, Logger log) {

        DockerMachineConfiguration config = dockerAccessContext.getMachine();
        if (dockerAccessContext.isSkipMachine()) {
            config = null;
        } else if (config == null) {
            Properties projectProps = dockerAccessContext.getProjectProperties();
            if (projectProps.containsKey(DockerMachineConfiguration.DOCKER_MACHINE_NAME_PROP)) {
                config = new DockerMachineConfiguration(
                    projectProps.getProperty(DockerMachineConfiguration.DOCKER_MACHINE_NAME_PROP),
                    projectProps.getProperty(DockerMachineConfiguration.DOCKER_MACHINE_AUTO_CREATE_PROP),
                    projectProps.getProperty(DockerMachineConfiguration.DOCKER_MACHINE_REGENERATE_CERTS_AFTER_START_PROP));
            }
        }

        List<DockerConnectionDetector.DockerHostProvider> ret = new ArrayList<>();
        ret.add(new DockerMachine(log, config));
        return ret;
    }
Return a list of providers which could delive connection parameters from
calling external commands. For this plugin this is docker-machine, but can be overridden
to add other config options, too.

@return list of providers or <code>null</code> if none are applicable
src/main/java/io/fabric8/maven/docker/service/DockerAccessFactory.java