docs: public void put(TypeMap<?, ?> typeMap) {
      TypePair<?, ?> typePair = TypePair.of(typeMap.getSourceType(),
          typeMap.getDestinationType(), typeMap.getName());
      synchronized (lock) {
        if (typeMaps.containsKey(typePair))
          throw new IllegalArgumentException("TypeMap exists in the store: " + typePair.toString());
        typeMaps.put(typePair, typeMap);
      }
    }