public static synchronized CancellationRegistry getInstance() {
    if (internalRef == null) {
      internalRef = new CancellationRegistry();
    }
    return internalRef;
  }
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