GWT: dynamic logging disabled by setting gwt-maven-plugin property disableClassMetadata to true

Question

We recently added dynamic logging to our gwt web application.

In order to achieve this we added a little javascript function to our webapp.gwt.xml file, which looks for the "?logging" parameter in the URL an returns either true or false.

<define-property name="dynamicLogging" values="TRUE, FALSE"/>
<property-provider name="dynamicLogging">
    <![CDATA[
        var logging = false;
        var strHref = window.location.href;

        if (strHref.indexOf("?") > -1) {
          var strQueryString = strHref.substr(strHref.indexOf("?")).toLowerCase();
          var aParam = strQueryString.split("&").toString();

          logging = aParam.indexOf("logging") > -1;
        }

        if (logging) {
          return 'TRUE'
        } else {
          return 'FALSE'
        }
    ]]>
</property-provider>

This function is used to activate the gwt.logging and setting the logLevel to "FINEST".

<set-property name="gwt.logging.enabled" value="TRUE">
    <when-property-is name="dynamicLogging" value="TRUE"/>
</set-property>

<set-property name="gwt.logging.logLevel" value="FINEST">
    <when-property-is name="dynamicLogging" value="TRUE"/>
</set-property>

In our configuration for the gwt-maven-plugin we set the disableClassMetadata property to true for generating smaller permutation files. We talk about ~90kb per permutation.

<plugin>
   <groupId>org.codehaus.mojo</groupId>
   <artifactId>gwt-maven-plugin</artifactId>
   <configuration>
      <style>OBF</style>
      <draftCompile>false</draftCompile>
      <disableClassMetadata>true</disableClassMetadata>
      <disableCastChecking>true</disableCastChecking>
      <disableAggressiveOptimization>false</disableAggressiveOptimization>
      <optimizationLevel>9</optimizationLevel>
      <enableClosureCompiler>true</enableClosureCompiler>
      <logLevel>INFO</logLevel>
   </configuration>
</plugin>

But this disables our dynamic logging! The only thing we found out so far is, that the JavaScript function works just fine in both configurations. (disableClassMetadata= true and false)

The description on the Maven GWT Plugin website gives no reasonable explanation why this could effect any code in the webapp.gwt.xml file.

Thanks for your help!