eclipse plugin - command uses visibleWhen not appear in context menu -

i wanna add context menu command when select java source files, context menu don't appear.
class type of java source files compilationunit eclipse plugin-in spy.

this plugin extension declaration(plugin.xml):

<extension          point="org.eclipse.ui.menus">       <menucontribution             locationuri="popup:org.eclipse.ui.popup.any?after=additions">          <command                commandid="xml2javacode.commands.samplecommand"                id="xml2javacode.menus.samplecommand"                mnemonic="s">             <visiblewhen>                <with                      variable="activemenuselection">                   <iterate>                      <instanceof                            value="org.eclipse.jdt.core.dom.compilationunit">                      </instanceof>                   </iterate>                </with>             </visiblewhen>          </command>       </menucontribution>    </extension> 

there several classes called compilationunit , have chosen wrong one.

 <instanceof      value="org.eclipse.jdt.internal.core.compilationunit">  </instanceof> 

works - but internal class should not reference it.

the usual way check java source file is:

<adapt type="org.eclipse.core.resources.iresource">     <test property="org.eclipse.core.resources.contenttypeid" value="org.eclipse.jdt.core.javasource" /> </adapt> 

which adapting selection iresource , checking content type id.