Bug 55604 [implementation] JavaOutlinePage should dispose CustomFiltersActionGroup
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaOutlinePage.java
}
	/**
	 * Returns the primary type of a class file.
	 * 
	 * @param classFile the class file
	 * @return returns the primary type of the class file, or <code>null</code>
	 * if is does not have one
	 */
	protected IType getMainType(IClassFile classFile) {
		try {
			IType type= classFile.getType();
			return type != null && type.exists() ? type : null;
		} catch (JavaModelException e) {
			return null;	
		}
	}
	
	/* (non-Javadoc)
	 * Method declared on Page
	 */
	public void init(IPageSite pageSite) {
		super.init(pageSite);
	}
	
	private void doPropertyChange(PropertyChangeEvent event) {
		if (fOutlineViewer != null) {
			if (MembersOrderPreferenceCache.isMemberOrderProperty(event.getProperty())) {
				fOutlineViewer.refresh(false);
			}
		}