private String writeResumeState(final Path path, final ResumeState modelObject)
            throws IOException {
        final String yamlString = dumpResumeStateInYaml(modelObject);
        if (path != null) {
            Files.write(path, yamlString.getBytes(), StandardOpenOption.CREATE, StandardOpenOption.WRITE, StandardOpenOption.TRUNCATE_EXISTING);
        }
        return yamlString;
    }
Runs the run subcommand.

It receives a ConfigSource and a String as parameters to be called from Ruby (embulk/runner.rb).
embulk-core/src/main/java/org/embulk/EmbulkRunner.java