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
* Returns a list of user properties defined in this element and somewhere
	 * up the inheritance chain.
	 * 
	 * @return The list of user properties.
	 */
	public List getUserProperties( )
	{
		List props = new ArrayList( );
		DesignElement e = this;
		while ( e != null )
		{
			List prop = e.getLocalUserProperties( );
			if ( prop != null )
			{
				props.addAll( prop );
			}
			e = e.getExtendsElement( );
		}
		return props;
	}
	/**
	 * Returns a list of user properties that are defined only on this element.
	 * 
	 * @return The list of user properties.
	 */
	public List getLocalUserProperties( )
	{
		if ( userProperties == null )
			return Collections.EMPTY_LIST;
		return new ArrayList( userProperties.values( ) );