a <a href="Servlet.html" title="interface in jakarta.servlet"><code>Servlet</code></a> or <a href="Filter.html" title="interface in jakarta.servlet"><code>Filter</code></a> may be further configured.

 <p>
 A Registration object whose <a href="#getClassName()"><code>getClassName()</code></a> method returns null is considered <i>preliminary</i>. Servlets and
 Filters whose implementation class is container implementation specific may be declared without any
 <tt>servlet-class</tt> or <tt>filter-class</tt> el