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
{
		if ( SessionHandleAdapter.getInstance( ).getReportDesignHandle( ) == null )
		{
			return GroupElementFactory.newGroupElement( SessionHandleAdapter.getInstance( )
					.getReportDesignHandle( ),
					Collections.EMPTY_LIST );
		}
		return GroupElementFactory.newGroupElement( SessionHandleAdapter.getInstance( )
				.getReportDesignHandle( ),
				modelList );
	}
	/**
	 * Checks if the library is included.
	 * 
	 * @param handle
	 * @return
	 */
	public static boolean isIncluded( LibraryHandle handle )
	{
		return handle.getNamespace( ) != null;
	}
	/**
	 * Get classes with default comparator
	 * 
	 * @return List of classes
	 */
	public static List getClasses( )
	{
		return getClasses( new AlphabeticallyComparator( ) );
	}