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
{
			extendsRef.resolve( resolvedParent );
			resolvedParent.addDerived( this );
		}
	}
	/**
	 * Gets the name of the element that this element extends.
	 * 
	 * @return The name of the extended element.
	 */
	public String getExtendsName( )
	{
		if ( extendsRef == null )
			return null;
		return StringUtil.buildQualifiedReference( extendsRef
				.getLibraryNamespace( ), extendsRef.getName( ) );
	}
	/**
	 * Returns the optional element name.
	 * <p>
	 * Part of: The name system.
	 * 
	 * @return Returns the name.
	 */
	public String getName( )
	{
		return name;
	}
	/**
	 * Sets the element name. The caller must have cleaned up any references to