anchor.diff:  
   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:
  +For instance the following creates two parent documents in the `my_parent` context:
   
   [source,js]
   --------------------------------------------------
  
positive.code: 
  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.
  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:
  
  
negative.code:   }
  }
  
  PUT my_index/doc/4?routing=1&refresh
  {
    "text": "This is a another child document",
    "my_join_field": {
  