href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link">String</a>&gt;</span>&nbsp;<span class="element-name">getCacheExtension</span>()</div>
<div class="block">Corresponds to a set of extension cache control directives.</div>
<dl class="notes">
<dt>Returns:</dt>
<dd>a mutable map of cache control extension names and their values. If a key has a null value, it will appear as
 a bare directive. If a key has a val