@Override
        public CheckAndMutateResult call(RegionObserver observer) throws IOException {
          return observer.preCheckAndMutateAfterRowLock(this, checkAndMutate, getResult());
        }
Supports Coprocessor 'bypass'.
@param checkAndMutate the CheckAndMutate object
@return true or false to return to client if default processing should be bypassed, or null
        otherwise
@throws IOException if an error occurred on the coprocessor
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java