@Override
  public void merge(final Mapper mergeWith, final MergeResult mergeResult)
      throws MergeMappingException {
    if (!(mergeWith instanceof ObjectMapper)) {
      mergeResult.addConflict(
          "Can't merge a non object mapping ["
              + mergeWith.name()
              + "] with an object mapping ["
              + name()
              + "]");
      return;
    }
    ObjectMapper mergeWithObject = (ObjectMapper) mergeWith;

    if (nested().isNested()) {
      if (!mergeWithObject.nested().isNested()) {
        mergeResult.addConflict(
            "object mapping [" + name() + "] can't be changed from nested to non-nested");
        return;
      }
    } else {
      if (mergeWithObject.nested().isNested()) {
        mergeResult.addConflict(
            "object mapping [" + name() + "] can't be changed from non-nested to nested");
        return;
      }
    }

    if (!mergeResult.simulate()) {
      if (mergeWithObject.dynamic != null) {
        this.dynamic = mergeWithObject.dynamic;
      }
    }

    doMerge(mergeWithObject, mergeResult);

    List<Mapper> mappersToPut = new ArrayList<>();
    List<ObjectMapper> newObjectMappers = new ArrayList<>();
    List<FieldMapper> newFieldMappers = new ArrayList<>();
    for (Mapper mapper : mergeWithObject) {
      Mapper mergeWithMapper = mapper;
      Mapper mergeIntoMapper = mappers.get(mergeWithMapper.simpleName());
      if (mergeIntoMapper == null) {
        // no mapping, simply add it if not simulating
        if (!mergeResult.simulate()) {
          mappersToPut.add(mergeWithMapper);
          MapperUtils.collect(mergeWithMapper, newObjectMappers, newFieldMappers);
        }
      } else if (mergeIntoMapper instanceof MetadataFieldMapper == false) {
        // root mappers can only exist here for backcompat, and are merged in Mapping
        mergeIntoMapper.merge(mergeWithMapper, mergeResult);
      }
    }
    if (!newFieldMappers.isEmpty()) {
      mergeResult.addFieldMappers(newFieldMappers);
    }
    if (!newObjectMappers.isEmpty()) {
      mergeResult.addObjectMappers(newObjectMappers);
    }
    // add the mappers only after the administration have been done, so it will not be visible to
    // parser (which first try to read with no lock)
    for (Mapper mapper : mappersToPut) {
      putMapper(mapper);
    }
  }