@Override
    public long getMemStoreFlushSize() {
      return getOrDefault(MEMSTORE_FLUSHSIZE_KEY, Long::valueOf, (long) -1);
    }
Returns the size of the memstore after which a flush to filesystem is triggered.
@return memory cache flush size for each hregion, -1 if not set.
@see #setMemStoreFlushSize(long)
hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java