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/api/command/ExtendsException.java
* The parent element not in component slot of report design.
	 */
	public static final String DESIGN_EXCEPTION_PARENT_NOT_IN_COMPONENT = MessageConstants.EXTENDS_EXCEPTION_PARENT_NOT_IN_COMPONENT;
	/**
	 * The library of the parent element is not included.
	 */
	public static final String DESIGN_EXCEPTION_PARENT_NOT_INCLUDE = MessageConstants.EXTENDS_EXCEPTION_PARENT_NOT_INCLUDE;
	/**
	 * The element has no parent, it can not be localized.
	 */
	
	public static final String DESIGN_EXCEPTION_NO_PARENT = MessageConstants.EXTENDS_EXCEPTION_NO_PARENT;
	
	/**
	 * Constructor.
	 * 
	 * @param obj
	 *            the element being changed.
	 * @param name
	 *            the value being set for the extends property.
	 * @param errCode
	 *            what went wrong.
	 */
	public ExtendsException( DesignElement obj, String name, String errCode )
	{
		super( obj, errCode );
		extendsName = name;
	}
	/**
	 * Constructor.