Bug 12116 [Contributions] widgets: MenuManager.setImageDescriptor() method needed
Currently there seems to be no API to assign image to menu item that contains submenu, the only way is to override MenuManager.fill() methods. That seems to be inconsistent.
bundles/org.eclipse.jface/src/org/eclipse/jface/action/MenuManager.java
public IContributionManagerOverrides getOverrides() {
        if (overrides == null) {
            if (parent == null) {
                overrides = new IContributionManagerOverrides() {
                    public Integer getAccelerator(IContributionItem item) {
                        return null;
                    }
                    public String getAcceleratorText(IContributionItem item) {
                        return null;
                    }
                    public Boolean getEnabled(IContributionItem item) {
                        return null;
                    }
                    public String getText(IContributionItem item) {
                        return null;
                    }
                };
            } else {
                overrides = parent.getOverrides();
            }
            super.setOverrides(overrides);
        }
        return overrides;
    }
    /**
     * Returns the parent contribution manager of this manger.
     * 
     * @return the parent contribution manager
     * @since 2.0
     */