private static Entry createEmptyEntry(TableName table, byte[] region, long seq) {
    long time = System.nanoTime();
    return new Entry(new WALKeyImpl(region, table, seq, time, HConstants.DEFAULT_CLUSTER_ID),
      new WALEdit());
  }
@param leaveOpen index to leave un-closed. -1 to close all.
@return the writer that's still open, or null if all were closed.
hbase-server/src/test/java/org/apache/hadoop/hbase/wal/TestWALSplit.java