*     exception itself.
   * @param executor the executor that runs {@code fallback} if the input fails
   */
  public <X extends Throwable> ClosingFuture<V> catching(
      Class<X> exceptionType, ClosingFunction<? super X, ? extends V> fallback, Executor executor) {
    return catchingMoreGeneric(exceptionType, fallback, executor);
  }

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            UserInfoCA ca = new UserInfoCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);

@Implements(DnsResolver::class)
class ShadowDnsResolver {
  var responder: (Request) -> Unit = {
    it.callback.onAnswer(listOf(), 0)
  }

  data class Request(
    val network: Network?,
    val domain: String,
    val nsType: Int,
    val flags: Int,
    val callback: DnsResolver.Callback<List<InetAddress>>,
  )

  @Implementation
  fun query(
    network: Network?,
    domain: String,

    MockCallback callback = new MockCallback("foo");
    addCallback(f, callback, directExecutor());
    f.set("foo");
  }

  public void testExecutorSuccess() {
    CountingSameThreadExecutor ex = new CountingSameThreadExecutor();
    SettableFuture<String> f = SettableFuture.create();
    MockCallback callback = new MockCallback("foo");
    Futures.addCallback(f, callback, ex);
    f.set("foo");

```

#### 6.2 Implementation Tasks
- [ ] Implement Witness RPC protocol
- [ ] Create witness service discovery
- [ ] Implement client registration
- [ ] Add notification callback mechanism
- [ ] Create resource monitoring
- [ ] Implement automatic re-registration
- [ ] Add cluster node tracking
- [ ] Create failover coordination

#### 6.3 Integration Points

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            UserCA ca = new UserCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            WebConfigCA ca = new WebConfigCA();
            aggsLambda.callback(ca);
            ca.getAggregationBuilderList().forEach(builder::subAggregation);

        FileConfigCQ cq = new FileConfigCQ();
        queryLambda.callback(cq);
        final Collection<FilterFunctionBuilder> list = new ArrayList<>();
        if (functionsLambda != null) {
            functionsLambda.callback((cqLambda, scoreFunctionBuilder) -> {
                FileConfigCQ cf = new FileConfigCQ();
                cqLambda.callback(cf);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            FileAuthenticationCA ca = new FileAuthenticationCA();
            aggsLambda.callback(ca);

        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            ElevateWordCA ca = new ElevateWordCA();
            aggsLambda.callback(ca);