@Override
 public void traverse(ObjectMapperListener objectMapperListener) {
   objectMapperListener.objectMapper(this);
   for (Mapper mapper : mappers.values()) {
     mapper.traverse(objectMapperListener);
   }
 }
 @Override
 public void includeInAllIfNotSet(Boolean includeInAll) {
   if (this.includeInAll == null) {
     this.includeInAll = includeInAll;
   }
   // when called from outside, apply this on all the inner mappers
   for (Mapper mapper : mappers.values()) {
     if (mapper instanceof AllFieldMapper.IncludeInAll) {
       ((AllFieldMapper.IncludeInAll) mapper).includeInAllIfNotSet(includeInAll);
     }
   }
 }
 @Override
 public UnmodifiableIterator<IndexShard> iterator() {
   return shards.values().iterator();
 }
 @Override
 public void close() {
   for (Mapper mapper : mappers.values()) {
     mapper.close();
   }
 }
 @Override
 public void traverse(FieldMapperListener fieldMapperListener) {
   for (Mapper mapper : mappers.values()) {
     mapper.traverse(fieldMapperListener);
   }
 }