code: synchronized Collection<Class<?>> processRemovedListeners(Collection<ProbeListener> listeners) {
          Set<Class<?>> classesToTransform = new HashSet<Class<?>>();
  
          for (ProbeListener listener : listeners) {
              Collection<ProbeImpl> listenerProbes = removeProbesByListener(listener);
              for (ProbeImpl probe : listenerProbes) {
                  Class<?> clazz = probe.getSourceClass();
                  removeInterestedByClass(clazz, listener);
                  if (removeListenerByProbe(probe, listener)) {
                      classesToTransform.add(clazz);
                  }
              }
          }
  
          return classesToTransform;
      }
docs: Process the recently unregistered listeners and calculate which classes
  need to be transformed to remove deactivated probes.
  
  @param listeners the collection of recently removed listeners
  
  @return the classes that must be retransformed to remove probes