default void preWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
    RegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException {
  }
Called before a {@link WALEdit} is writen to WAL.
<p>
The method is marked as deprecated in 2.0.0, but later we abstracted the WALKey interface for
coprocessors, now it is OK to expose this to coprocessor users, so we revert the deprecation.
But you still need to be careful while changing {@link WALEdit}, as when reaching here, if you
add some cells to WALEdit, it will only be written to WAL but no in memstore, but when
replaying you will get these cells and there are CP hooks to intercept these cells.
<p>
See HBASE-28580.
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/WALObserver.java