public Long appendBatchIndexAsync(final List<IndexEntry> indexArray) {
        long maxFlushPosition = -1;
        for (int i = 0; i < indexArray.size(); i++) {
            final IndexEntry index = indexArray.get(i);
            final long logIndex = index.getLogIndex();
            if (logIndex == getLastLogIndex() + 1) {
                final Pair<Integer, Long> flushPair = appendIndexAsync(logIndex, index.getPosition(),
                    index.getLogType() == 1 ? IndexType.IndexSegment : IndexType.IndexConf);
                maxFlushPosition = Math.max(maxFlushPosition, flushPair.getSecond());
            }
        }
        return maxFlushPosition;
    }
Append IndexEntryArray(logIndex , position, indexType)
@return max expectFlushPosition
jraft-extension/java-log-storage-impl/src/main/java/com/alipay/sofa/jraft/storage/db/IndexDB.java