JPA Method
in javax.persistence.EntityGraph

Subgraph<X> addKeySubgraph(
  Attribute<T,X> attribute
)


Add a node to the graph that corresponds to a map key that is a managed type. This allows for construction of multi-node entity graphs that include related managed types.
Parameters:
attribute - attribute
Return:
subgraph for the key attribute
Throws:
IllegalArgumentException - if the attribute's target type is not an entity
IllegalStateException - if this EntityGraph has been statically defined
Since:
JPA 2.1