/** The key of the configuration. e.g. _version */
    String INDEX_FIELD_VERSION = "index.field.version";

    /** The key of the configuration. e.g. _seq_no */
    String INDEX_FIELD_seq_no = "index.field.seq_no";

    /** The key of the configuration. e.g. _primary_term */
    String INDEX_FIELD_primary_term = "index.field.primary_term";

    /** The key of the configuration. e.g. lang */

    }

    public boolean delete(final String index, final String id, final Number seqNo, final Number primaryTerm) {
        try {
            final DeleteRequestBuilder builder = client.prepareDelete().setIndex(index).setId(id).setRefreshPolicy(RefreshPolicy.IMMEDIATE);
            if (seqNo != null) {
                builder.setIfSeqNo(seqNo.longValue());
            }
            if (primaryTerm != null) {