@Override
  public void merge(final Mapper mergeWith, final MergeContext mergeContext)
      throws MergeMappingException {
    if (!(mergeWith instanceof ObjectMapper)) {
      mergeContext.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()) {
        mergeContext.addConflict(
            "object mapping [" + name() + "] can't be changed from nested to non-nested");
        return;
      }
    } else {
      if (mergeWithObject.nested().isNested()) {
        mergeContext.addConflict(
            "object mapping [" + name() + "] can't be changed from non-nested to nested");
        return;
      }
    }

    doMerge(mergeWithObject, mergeContext);

    List<Mapper> mappersToTraverse = new ArrayList<Mapper>();
    synchronized (mutex) {
      for (Mapper mergeWithMapper : mergeWithObject.mappers.values()) {
        Mapper mergeIntoMapper = mappers.get(mergeWithMapper.name());
        if (mergeIntoMapper == null) {
          // no mapping, simply add it if not simulating
          if (!mergeContext.mergeFlags().simulate()) {
            putMapper(mergeWithMapper);
            mappersToTraverse.add(mergeWithMapper);
          }
        } else {
          if ((mergeWithMapper instanceof MultiFieldMapper)
              && !(mergeIntoMapper instanceof MultiFieldMapper)) {
            MultiFieldMapper mergeWithMultiField = (MultiFieldMapper) mergeWithMapper;
            mergeWithMultiField.merge(mergeIntoMapper, mergeContext);
            if (!mergeContext.mergeFlags().simulate()) {
              putMapper(mergeWithMultiField);
              // now, record mappers to traverse events for all mappers
              for (Mapper mapper : mergeWithMultiField.mappers().values()) {
                mappersToTraverse.add(mapper);
              }
            }
          } else {
            mergeIntoMapper.merge(mergeWithMapper, mergeContext);
          }
        }
      }
    }
    // call this outside of the mutex
    for (Mapper mapper : mappersToTraverse) {
      mapper.traverse(mergeContext.newFieldMappers());
      mapper.traverse(mergeContext.newObjectMappers());
    }
  }
  @Override
  public void merge(final Mapper mergeWith, final MergeContext mergeContext)
      throws MergeMappingException {
    if (!(mergeWith instanceof ObjectMapper)) {
      mergeContext.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()) {
        mergeContext.addConflict(
            "object mapping [" + name() + "] can't be changed from nested to non-nested");
        return;
      }
    } else {
      if (mergeWithObject.nested().isNested()) {
        mergeContext.addConflict(
            "object mapping [" + name() + "] can't be changed from non-nested to nested");
        return;
      }
    }

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

    doMerge(mergeWithObject, mergeContext);

    List<Mapper> mappersToPut = new ArrayList<>();
    FieldMapperListener.Aggregator newFieldMappers = new FieldMapperListener.Aggregator();
    ObjectMapperListener.Aggregator newObjectMappers = new ObjectMapperListener.Aggregator();
    synchronized (mutex) {
      for (Mapper mapper : mergeWithObject.mappers.values()) {
        Mapper mergeWithMapper = mapper;
        Mapper mergeIntoMapper = mappers.get(mergeWithMapper.name());
        if (mergeIntoMapper == null) {
          // no mapping, simply add it if not simulating
          if (!mergeContext.mergeFlags().simulate()) {
            mappersToPut.add(mergeWithMapper);
            mergeWithMapper.traverse(newFieldMappers);
            mergeWithMapper.traverse(newObjectMappers);
          }
        } else {
          mergeIntoMapper.merge(mergeWithMapper, mergeContext);
        }
      }
      if (!newFieldMappers.mappers.isEmpty()) {
        mergeContext.docMapper().addFieldMappers(newFieldMappers.mappers);
      }
      if (!newObjectMappers.mappers.isEmpty()) {
        mergeContext.docMapper().addObjectMappers(newObjectMappers.mappers);
      }
      // and 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);
      }
    }
  }