Eclipse plugins - Add a menucontribution to Toolbar dynamically - eclipse

Question

Is it possible to add menucontribution, basically a new button, to the toolbar:org.eclipse.ui.main.toolbar dynamically?
I tried with AbstractContributionFactory but it seems to be bugged, since the createContributionItems is never called.
My code so far tries to add a new button to the Eclipse toolbar after pressing another button. The thing is that the createContributionItems is never called so "Creating Stuff" never appears:
//If a certain button is pressed run will be executed
public void run(IAction action) {
MessageDialog.openInformation(
window.getShell(),
"Runtimecommands",
"Hello, Eclipse world");
IMenuService menuService = (IMenuService) PlatformUI.getWorkbench().getService(IMenuService.class);
AbstractContributionFactory factory = new AbstractContributionFactory("toolbar:org.eclipse.ui.main.toolbar", null)
#Override
public void createContributionItems(IServiceLocator serviceLocator, IContributionRoot additions) {
System.out.println("Creating Stuff");
};
menuService.addContributionFactory(factory);
}
And my current plugin.xml
<plugin>
<extension
point="org.eclipse.ui.actionSets">
<actionSet
label="Sample Action Set"
visible="true"
id="com.dynamo.actionSet">
<menu
label="Sample &Menu"
id="sampleMenu">
<separator
name="sampleGroup">
</separator>
</menu>
<action
label="&Sample Action"
icon="icons/sample.gif"
class="com.dynamo.actions.SampleAction"
tooltip="Hello, Eclipse world"
menubarPath="sampleMenu/sampleGroup"
toolbarPath="sampleGroup"
id="com.dynamo.actions.SampleAction">
</action>
</actionSet>
</extension>
</plugin>
Tks for your attention.