public synchronized void registerMessage(AdminRequest msg) {
    Key key = new Key(msg.getSender(), msg.getMsgId());
    map.put(key, msg);
  }
This class provides a way for a {@link CancellationMessage} to find its prey. An
{@link AdminRequest} that implements {@link Cancellable} should register with this class before
doing any work, and deregister just before returning it's response.
geode-core/src/main/java/org/apache/geode/internal/admin/remote/CancellationRegistry.java