&nbsp;<span class="element-name">getPropertyNames</span>()</div>
<div class="block">Returns an immutable <a href="https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Collection.html" title="class or interface in java.util" class="external-link"><code>collection</code></a> containing the property names available within the
 context of the current request/response exchange context.
 <p>
 Use the <a href="#getProperty(java.lang.String)"><code>getProperty(java.lang.String)</code></a> method w