private void registerClassDefinitions(
     final Collection<ClassDefinition> classDefinitions, boolean checkClassDefErrors) {
   final Map<Integer, ClassDefinition> classDefMap =
       new HashMap<Integer, ClassDefinition>(classDefinitions.size());
   for (ClassDefinition cd : classDefinitions) {
     if (classDefMap.containsKey(cd.getClassId())) {
       throw new HazelcastSerializationException(
           "Duplicate registration found for class-id[" + cd.getClassId() + "]!");
     }
     classDefMap.put(cd.getClassId(), cd);
   }
   for (ClassDefinition classDefinition : classDefinitions) {
     registerClassDefinition(classDefinition, classDefMap, checkClassDefErrors);
   }
 }