public static Map<String, String> getFilterInitParams( Document webXml, String filterName )
    {
        return getInitParams( "filter", webXml, filterName );
    }
Retrieves a map of init param/values for a particular filter from a web.xml document.

For filter 'message' of this web.xml document, returns a map with two entries: foo-&gt; bar, test-&gt;value.
&lt;filter&gt;
  &lt;filter-name&gt;message&lt;/filter-name&gt;
  &lt;filter-class&gt;com.acme.filter.MessageFilter&lt;/filter-class&gt;
  &lt;init-param&gt;
    &lt;param-name&gt;foo&lt;/param-name&gt;
    &lt;param-value&gt;bar&lt;/param-value&gt;
  &lt;/init-param&gt;
  &lt;init-param&gt;
    &lt;param-name&gt;test&lt;/param-name&gt;
    &lt;param-value&gt;value&lt;/param-value&gt;
  &lt;/init-param&gt;
&lt;/filter&gt;

Parameters with no or empty name are ignored. When multiple parameters have the same name, only one of them is
returned.

@param webXml web.xml document, parsed as XML (cannot be null)
@param filterName The name of the filter (cannot be null or empty).
@return A map (possibly empty, but never null).
xmppserver/src/main/java/org/jivesoftware/util/WebXmlUtils.java