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
*            name of the property.
	 * @param value
	 *            value needs to set.
	 * @throws SemanticException
	 *             if the value is invalid for the property, or the property is
	 *             undefined on the elements.
	 */
	public final void setStringProperty( String propName, String value )
			throws SemanticException
	{
		setProperty( propName, value );
	}
	/**
	 * Checks whether the <code>element</code> is a member of
	 * <code>GroupElementHandle</code>.
	 * 
	 * @param element
	 *            the element to check
	 * @return <code>true</code> if the element is in the list, otherwise
	 *         <code>false</code>.
	 */
	abstract protected boolean isInGroup( DesignElementHandle element );
	/**
	 * An iterator over the properties defined for elements that in the group
	 * element.
	 */
	class GroupPropertyIterator implements Iterator
	{
		/**
		 * The property iterator to traverse the properties.