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
* name space rules. This class simply maintains the name itself.
	 */
	protected String name = null;
	/**
	 * Elements are structured in a hierarchy. The implementation of the
	 * container-to-child relationship must be defined in derived classes. This
	 * base class defines the child-to-container relationship.
	 */
	protected DesignElement container = null;
	/**
	 * Slot in the container in which this element resides.
	 */
	protected int containerSlotID = NO_SLOT;
	/**
	 * Listeners are the objects that want to be notified of events. Contents
	 * are of type Listener. Created only when needed.
	 */
	protected ArrayList listeners = null;
	/**
	 * Values for non-intrinsic property values. The contents are of type
	 * Object.
	 */
	protected Map propValues = new HashMap( );
	/**
	 * Definitions for user-defined properties. Contents are of type
	 * UserPropertyDefn.
	 */
	protected HashMap userProperties = null;
	/**
	 * Support for inheritance. Represents the resolved or unresolved element