public void setWriteEntry(MultiVersionConcurrencyControl.WriteEntry writeEntry) {
    assert this.writeEntry == null;
    this.writeEntry = writeEntry;
    // Set our sequenceid now using WriteEntry.
    this.sequenceId = writeEntry.getWriteNumber();
  }
Use it to complete mvcc transaction. This WALKeyImpl was part of (the transaction is started
when you call append; see the comment on FSHLog#append). To complete call
{@link MultiVersionConcurrencyControl#complete(MultiVersionConcurrencyControl.WriteEntry)} or
{@link MultiVersionConcurrencyControl#complete(MultiVersionConcurrencyControl.WriteEntry)}
@return A WriteEntry gotten from local WAL subsystem.
@see #setWriteEntry(MultiVersionConcurrencyControl.WriteEntry)
hbase-server/src/main/java/org/apache/hadoop/hbase/wal/WALKeyImpl.java