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
* up the containment hierarchy if it'd defined to no inherit.
	 * <p>
	 * Part of: Property value system.
	 * 
	 * @param module
	 *            the module
	 * @param prop
	 *            definition of the property to get
	 * @return The property value, or null if no value is set.
	 */
	public Object getProperty( Module module, ElementPropertyDefn prop )
	{
		Object value = getStrategy( ).getPropertyExceptRomDefault( module,
				this, prop );
		if ( value != null )
			return value;
		return prop.getDefault( );
	}
	/**
	 * Gets the search strategy for this element.
	 * 
	 * @return the search strategy for this element.
	 */
	public PropertySearchStrategy getStrategy( )
	{
		return PropertySearchStrategy.getInstance( );
	}
	/**
	 * Gets selector of the given slot of this element. The selector is kind of
	 * predefined style, and its style property value can be applied on contents