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/command/ExtendsCommand.java
}
	/**
	 * Localize the element, break the parent/child relationship and set all the
	 * extended properties locally.
	 * 
	 * @throws SemanticException
	 * 
	 */
	public void localizeElement( ) throws SemanticException
	{
		
		DesignElement parent = element.getExtendsElement( );
		if ( parent == null )
			throw new ExtendsException( element, parent,
					ExtendsException.DESIGN_EXCEPTION_NO_PARENT );
		
		
		
		ContentIterator parentIter = new ContentIterator( parent );
		ContentIterator childIter = new ContentIterator( element );
		while ( parentIter.hasNext( ) )
		{
			assert childIter.hasNext( );
			DesignElement e1 = (DesignElement) parentIter.next( );
			DesignElement e2 = (DesignElement) childIter.next( );
			assert e1.getDefn( ) == e2.getDefn( );
			assert e2.getBaseId( ) == e1.getID( );
		}