@SuppressWarnings("deprecation")  // https://github.com/embulk/embulk/issues/1304
    private String dumpDataSourceInYaml(final DataSource modelObject) {
        final Object object = this.embed.dumpObjectFromDataSource(modelObject);
        final YamlProcessor yamlProc = YamlProcessor.create(false);
        return yamlProc.dump(object);
    }
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