Bug 167545 Copy a cascading parameter group and paste it to another parameter group causes an exception thrown
Steps to reproduce: 1.Copy a cascading parameter group using short cut key "Ctrl+x"/"Ctrl+c", or choosing context menu "Cut"/"Copy"; 2.Paste it to another parameter group using short cut key "Ctrl+v", or choosing context menu "Paste"; Expected result: The source one is pasted in the destination. Actual result: An exception thrown org.eclipse.birt.report.model.api.command.ContentException: The Cascading Parameter Group("Source") is not allowed in the slot (parameters) of Parameter Group("Destination").
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
Iterator iterator = getBindingColumnIterator( elementHandle );
				while ( iterator.hasNext( ) )
				{
					subBindingList.add( iterator.next( ) );
				}
				bindingList.addAll( 0, subBindingList );
			}
		}
		return bindingList;
	}
	/**
	 * Returns the element handle which can save binding columns the given
	 * element
	 * 
	 * @param handle
	 *            the handle of the element which needs binding columns
	 * @return the holder for the element,or itself if no holder available
	 */
	public static ReportItemHandle getBindingHolder( DesignElementHandle handle )
	{
		if ( handle instanceof ReportElementHandle )
		{
			if ( handle instanceof ListingHandle )
			{
				return (ReportItemHandle) handle;
			}
			if ( handle instanceof ReportItemHandle )
			{
				if ( ( (ReportItemHandle) handle ).getDataSet( ) != null
						|| ( (ReportItemHandle) handle ).columnBindingsIterator( )