Bug 138562 Splite extendsexcpetion to seperate sub class
The suggestion is Parent invalid Cycle extends Different type extends Not top level extends
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
*            the definition of element to insert
	 * @return false if the module is a library and the element to insert is a
	 *         template element or its content is a template element; or the
	 *         container is report design and slot is component slot and the
	 *         element to insert is a template element or its content is a
	 *         template element; otherwise true
	 */
	private boolean canContainTemplateElement( Module module, int slotID,
			IElementDefn defn )
	{
		
		
		if ( defn != null
				&& defn.isKindOf( MetaDataDictionary.getInstance( ).getElement(
						ReportDesignConstants.TEMPLATE_ELEMENT ) ) )
		{
			
			
			DesignElement container = this;
			int slot = slotID;
			while ( container != null )
			{
				if ( ( container instanceof Module && slot == Module.COMPONENT_SLOT )
						|| container instanceof Library )
					return false;
				slot = container.getContainerSlot( );
				container = container.getContainer( );
			}
			if ( module instanceof Library )
				return false;