Bug 152430 Key can modify to empty string
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/PropertyMaskHandle.java
* 
	 * @param mask
	 *            the mask to set
	 * @throws SemanticException
	 *             if the mask is not in the choice list.
	 */
	public void setMask( String mask ) throws SemanticException
	{
		setProperty( PropertyMask.MASK_MEMBER, mask );
	}
	/**
	 * Returns the property name.
	 * 
	 * @return the property name
	 */
	public String getName( )
	{
		return getStringProperty( PropertyMask.NAME_MEMBER );
	}
	/**
	 * Sets the property name.
	 * 
	 * @param name
	 *            the property name to set
	 */
	public void setName( String name )
	{
		setPropertySilently( PropertyMask.NAME_MEMBER, name );
	}
}