Bug 146481 Name is not necessary for extended element
Steps to reproduce: 1.New a label named "label" in library 2.New a report, extend lib.label Expected result: No name for the extended label Actual result: "label" is added as the name of label in report. It's not reasonable because "Restore Properties" is enabled even without properties change.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/GroupElementHandle.java
* Given a collection of elements, user can ask for their common
 * properties(including user property definitions). Also, return a list of
 * values that are identical for all items. Finally, return an indication of
 * whether all elements are of the same type.
 * <p>
 * This class also supports a collection of elements contains some objects that
 * are not a <code>DesignElementHandle</code> or its subclass. For this case,
 * <code>getCommonProperties</code> always returns an empty list.
 * <p>
 * For BIRT UI usage, the attributes view will go blank if the providing
 * elements are not of the same type, the property sheet will show the common
 * properties(including user property definitions).
 * <p>
 * This handle is mutable, it can be kept. The query results changed as the
 * given elements themselves changed.
 * <p>
 * Note that the Model special handling of the case where all elements are the
 * same type: in this case, by definition, all BIRT-defined properties are the
 * same. (User-defined properties may differ.)
 */
abstract public class GroupElementHandle
{
	/**
	 * Default constructor.
	 */
	public GroupElementHandle( )
	{
	}
	/**
	 * Returns the list that contains the group of design elements. Contents of