assertFalse(extraFieldNames.contains("_version"), "Reserved field _version should be excluded");
        assertFalse(extraFieldNames.contains("_seq_no"), "Reserved field _seq_no should be excluded");
        assertFalse(extraFieldNames.contains("_primary_term"), "Reserved field _primary_term should be excluded");
    }

    @Test

    }

    @Test
    public void test_parseJson_operationDocument() {
        final String json = "{\"_index\":\"fess_config.coordinator\",\"_id\":\"reindex\","
                + "\"found\":true,\"_seq_no\":5,\"_primary_term\":1," + "\"_source\":{\"type\":\"operation\",\"name\":\"reindex\","
                + "\"instanceId\":\"node1@host1\",\"hostname\":\"host1\","

            final long seqNo = getLongValue(result, "_seq_no");
            final long primaryTerm = getLongValue(result, "_primary_term");
            try (CurlResponse deleteResponse = ComponentUtil.getCurlHelper() //
                    .delete("/" + getIndexName() + "/_doc/" + operationName //
                            + "?refresh=true&if_seq_no=" + seqNo + "&if_primary_term=" + primaryTerm) //

                    return "id";
                case FessConfig.INDEX_FIELD_VERSION:
                    return "_version";
                case FessConfig.INDEX_FIELD_seq_no:
                    return "_seq_no";
                case FessConfig.INDEX_FIELD_primary_term:
                    return "_primary_term";
                case FessConfig.INDEX_FIELD_LANG:
                    return "lang";

        }

        @Override
        public String getIndexFieldVersion() {
            return "_version";
        }

        @Override
        public String getIndexFieldSeqNo() {
            return "_seq_no";
        }

        @Override
        public String getIndexFieldPrimaryTerm() {
            return "_primary_term";
        }

        @Override

index.field.doc_id=doc_id
# Field name for internal ID in the index.
index.field.id=_id
# Field name for version in the index.
index.field.version=_version
# Field name for sequence number in the index.
index.field.seq_no=_seq_no
# Field name for primary term in the index.
index.field.primary_term=_primary_term
# Field name for language in the index.
index.field.lang=lang
# Field name for cache status in the index.

    /** 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 */

        if (indexOption != null) {
            indexOption.callback(builder);
        }
        final Long seqNo = esEntity.asDocMeta().seqNo();
        if (seqNo != null && seqNo.longValue() != SequenceNumbers.UNASSIGNED_SEQ_NO) {
            esEntity.asDocMeta().seqNo(seqNo);
        }
        final Long primaryTerm = esEntity.asDocMeta().primaryTerm();

        }

        public Long version() {
            return version;
        }

        public DocMeta seqNo(Long seqNo) {
            this.seqNo = seqNo;
            return this;
        }

        public Long seqNo() {
            return seqNo;
        }

        public DocMeta primaryTerm(Long primaryTerm) {
            this.primaryTerm = primaryTerm;
            return this;

        }

        public Long version() {
            return version;
        }

        public DocMeta seqNo(Long seqNo) {
            this.seqNo = seqNo;
            return this;
        }

        public Long seqNo() {
            return seqNo;
        }

        public DocMeta primaryTerm(Long primaryTerm) {
            this.primaryTerm = primaryTerm;
            return this;