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/plugin/OdaExtensibilityProvider.java
public OdaExtensibilityProvider( DesignElement element, String extensionID )
	{
		super( element );
		this.extensionID = extensionID;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.extension.ExtensibilityProvider#getPropertyDefns()
	 */
	public List getPropertyDefns( )
	{
		if ( getExtDefn( ) == null )
			return Collections.EMPTY_LIST;
		return getExtDefn( ).getProperties( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.extension.ExtensibilityProvider#getPropertyDefn(java.lang.String)
	 */
	public IPropertyDefn getPropertyDefn( String propName )
	{
		if ( getExtDefn( ) == null )
			return null;
		return (ElementPropertyDefn) getExtDefn( ).getProperty( propName );
	}
	/*
	 * (non-Javadoc)
	 *