protected <O, R> R execOperationWithResult(
    final ObserverOperationWithResult<O, R> observerOperation) throws IOException {
    boolean bypass = execOperation(observerOperation);
    R result = observerOperation.getResult();
    return bypass == observerOperation.isBypassable() ? result : null;
  }
Do not call with an observerOperation that is null! Have the caller check.
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorHost.java