Bug 210609 [Smoke]Crosstab is failed to preview in runtime
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/extension/ExtensionPointManager.java
{
	private Map reportItemUIMap = null;
	private Map menuBuilderMap = null;
	private Map providerFactoryMap = null;
	private static ExtensionPointManager instance = null;
	private ExtensionPointManager( )
	{
	}
	public static ExtensionPointManager getInstance( )
	{
		if ( instance == null )
		{
			synchronized ( ExtensionPointManager.class )
			{
				if ( instance == null )
				{
					instance = new ExtensionPointManager( );
				}
			}
		}
		return instance;
	}
	/**
	 * Gets the list of all the extended element points.
	 * 
	 * @return Returns the list of all the extended element point
	 *         (ExtendedElementUIPoint).