anchor.diff:  
   The parent-join creates one field to index the name of the relation
   within the document (`my_parent`, `my_child`, ...).
  -It also creates one field per parent/child relation. The name of this field is
  -the name of the `join` field followed by `#` and the name of the parent in the relation.
  +
  +It also creates one field per parent/child relation.
  +The name of this field is the name of the `join` field followed by `#` and the
  +name of the parent in the relation.
   So for instance for the `my_parent` => [`my_child`, `another_child`] relation,
   the `join` field creates an additional field named `my_join_field#my_parent`.
  +
   This field contains the parent `_id` that the document links to
   if the document is a child (`my_child` or `another_child`) and the `_id` of
   document if it's a parent (`my_parent`).
  +
   When searching an index that contains a `join` field, these two fields are always
   returned in the search response:
   
  
positive.code: 
  To index a document with a join, the name of the relation and the optional parent
  of the document must be provided in the `source`.
  For instance the following creates a parent document in the `my_parent` context:
  
  [source,js]
  --------------------------------------------------
  
negative.code: 
  <1> `my_parent` is parent of `my_child`.
  
  And multiple levels of parent/child:
  
  [source,js]
  --------------------------------------------------
  