}
                    }

                    docMap.put(fessConfig.getIndexFieldId(), hit.getId());
                    docMap.put(fessConfig.getIndexFieldVersion(), hit.getVersion());
                    docMap.put(fessConfig.getIndexFieldSeqNo(), hit.getSeqNo());
                    docMap.put(fessConfig.getIndexFieldPrimaryTerm(), hit.getPrimaryTerm());

            if (source != null) {
                final Map<String, Object> docMap = new HashMap<>(source);
                docMap.put(fessConfig.getIndexFieldId(), hit.getId());
                docMap.put(fessConfig.getIndexFieldVersion(), hit.getVersion());
                docMap.put(fessConfig.getIndexFieldSeqNo(), hit.getSeqNo());
                docMap.put(fessConfig.getIndexFieldPrimaryTerm(), hit.getPrimaryTerm());
                return docMap;

     * The value is, e.g. _version <br>
     * comment: Field name for version in the index.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getIndexFieldVersion();

    /**
     * Get the value for the key 'index.field.seq_no'. <br>
     * The value is, e.g. _seq_no <br>
     * comment: Field name for sequence number in the index.