e">keySubgraph</span></div>
<div class="block">(Optional) If the attribute references a Map type, this element
 can be used to specify a subgraph for the Key in the case of an
 Entity key type. A <code>keySubgraph</code> can not be specified
 without the <code>Map</code> attribute also being specified. If the
 target type has inheritance, multiple subgraphs can be specified.
 These additional subgraphs are intended to add subclass-specific
 attributes. Superclass subgraph entries are merged into subclass
 s