Bug 92777 [Contributions] Spec clarification: ContributionItem.getParent() can return null
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ContributionItem.java
}
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method returns <code>false</code>. Subclasses may override.
     */
    public boolean isGroupMarker() {
        return false;
    }
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method returns <code>false</code>. Subclasses may override.
     */
    public boolean isSeparator() {
        return false;
    }
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method returns the value recorded in an internal state variable,
     * which is <code>true</code> by default. <code>setVisible</code>
     * should be used to change this setting.
     */
    public boolean isVisible() {
        return visible;
    }
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method stores the value in an internal state variable,
     * which is <code>true</code> by default.
     */
    public void setVisible(boolean visible) {