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
* @return the iterator of binding columns
	 */
	public static Iterator getBindingColumnIterator( DesignElementHandle handle )
	{
		if ( handle instanceof ReportItemHandle )
		{
			return ( (ReportItemHandle) handle ).columnBindingsIterator( );
		}
		return Collections.EMPTY_LIST.iterator( );
	}
	/**
	 * Return the expression for the given binding column based on the given
	 * element
	 * 
	 * @param baseElement
	 *            the base element
	 * @param column
	 *            the binding column
	 * @return the expression for the column
	 */
	public static String getBindingexpression( DesignElementHandle baseElement,
			ComputedColumnHandle column )
	{
		String exp = IReportElementConstants.BINDING_COLUMN_PREFIX;
		for ( int i = 0; i < getBindingLevel( column.getElementHandle( ),
				baseElement ); i++ )
		{
			exp += IReportElementConstants.OUTER_BINDING_COLUMN_PREFIX;
		}
		exp += "[\"" + DEUtil.escape( column.getName( ) ) + "\"]";