Bug 207036 [Regression] The chart in an old report design can not be rendered [13]
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/render/DeferredCacheManager.java
DeferredCache createDeferredCache( )
	{
		DeferredCache dc = new DeferredCache( fDeviceRenderer, fChart );
		fDeferredCacheList.add( dc );
		return dc;
	}
	/**
	 * Create <code>DeferredCache</code> instance for signle case, the related
	 * <code>DeferredCache</code> will be only created once.
	 * 
	 * @return instance of <code>DeferredCache</code>.
	 */
	DeferredCache createSingleDeferredCache( )
	{
		if ( fSingleDC != null )
		{
			return fSingleDC;
		}
		fSingleDC = new DeferredCache( fDeviceRenderer, fChart );
		fDeferredCacheList.add( fSingleDC );
		return fSingleDC;
	}
	
	/**
	 * Flush all <code>DeferredCache</code> in the mananger.
	 * 
	 * @throws ChartException
	 */
	public void flushAll( ) throws ChartException
	{