private void updateLocalAndReverseMaps(Object key, Object value) {
    reverseMap.saveToPending(key, value);
    if (value instanceof PdxType) {
      PdxType type = (PdxType) value;
      synchronized (classToType) {
        if (type.getClassName().equals(JSONFormatter.JSON_CLASSNAME)) {
          return; // no need to include here
        }
        CopyOnWriteHashSet<PdxType> pdxTypeSet = classToType.get(type.getClassName());
        if (pdxTypeSet == null) {
          pdxTypeSet = new CopyOnWriteHashSet<>();
        }
        pdxTypeSet.add(type);
        classToType.put(type.getClassName(), pdxTypeSet);
      }
    }
  }
adds a PdxType for a field to a {@code className => Set<PdxType>} map
geode-core/src/main/java/org/apache/geode/pdx/internal/PeerTypeRegistration.java