@SuppressWarnings("unused")
  default void preTruncateRegion(final ObserverContext<MasterCoprocessorEnvironment> c,
    RegionInfo regionInfo) {
  }
Called before the truncate region procedure is called.
@param c          The environment to interact with the framework and master
@param regionInfo The Region being truncated
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java