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/parser/ReportElementState.java
long elementID = content.getID( );
		if ( elementID > 0 )
		{
			DesignElement element = module.getElementByID( elementID );
			
			assert element != content;
			if ( element == null )
				module.addElementID( content );
			else
			{
				handler
						.getErrorHandler( )
						.semanticError(
								new DesignParserException(
										new String[]{content.getIdentifier( ),
												element.getIdentifier( )},
										DesignParserException.DESIGN_EXCEPTION_DUPLICATE_ELEMENT_ID ) );
				return false;
			}
		}
		
		container.getSlot( slotID ).add( content );
		
		content.setContainer( container, slotID );
		return true;
	}
	/**
	 * Initializes a report element with "name" and "extends" property.