@Override
        public Result call(RegionObserver observer) throws IOException {
          return observer.postAppend(this, append, result, edit);
        }
@param append Append object
@param result the result returned by the append
@param edit   The WALEdit object.
@throws IOException if an error occurred on the coprocessor
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java