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
}
	/**
	 * If the given property is a common property, value will be returned as a
	 * string if all values within the group of elements are equal and one of
	 * them has a local value. If the property is not a common property or none
	 * of them has a local value, return <code>null</code>.
	 * 
	 * @param propName
	 *            name of the property.
	 * @return the value as a string if the property is a common property, all
	 *         the elements have the same value and one of them has a local
	 *         value. Return null if the property is not a common property or
	 *         elements have different values for this property or none of them
	 *         has a local value.
	 * @see GroupPropertyHandle#getLocalStringValue()
	 */
	public final String getLocalStringProperty( String propName )
	{
		GroupPropertyHandle propHandle = getPropertyHandle( propName );
		if ( propHandle == null )
			return null;
		return propHandle.getLocalStringValue( );
	}
	/**
	 * Indicates whether the group of element share the same value for this
	 * property.
	 * <p>
	 * If all element has a <code>null</code> value for this property, it is
	 * considered that they share the same value.
	 *