:</span></dt>
<dd><code>attributeName</code> - name of the attribute</dd>
<dd><code>type</code> - entity subclass</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>subgraph for the key attribute</dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/IllegalArgumentException.html?is-external=true" title="class or interface in java.lang" class="externalLink">IllegalArgumentException</a></code> - if the attribut