public static File prepareAbsoluteSourceDirPath(MojoParameters params, String path) {
        return prepareAbsolutePath(params.getProject().getBasedir(), params.getSourceDirectory(), path);
    }
Return the first non null registry given. Use the env var DOCKER_REGISTRY as final fallback
@param checkFirst list of registries to check
@return registry found or null if none.
src/main/java/io/fabric8/maven/docker/util/EnvUtil.java