Bug 121498 When datasource/dataset deleted, the datasource/dataset property binding element haven't been deleted
When deleted the datasource/dataset, the datasource/dataset property binding element haven't been deleted. Expected result: This operation must be a transaction.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
/**
	 * Returns an iterator over the clients of this element. Useful only for
	 * styles. Returns a list of all the elements that use this style.
	 * 
	 * @return an iterator over the clients of this element. Each item returned
	 *         by the iterator's <code>getNext( )</code> method is of type
	 *         {@link DesignElementHandle}. Nothing will be iterated over an
	 *         element that is not <code>ReferenceableElement</code>.
	 */
	public Iterator clientsIterator( )
	{
		return new ClientIterator( this );
	}
	/**
	 * Returns a array of valid choices for a property.
	 * 
	 * @param propName
	 *            the property name
	 * @return a array containing choices for the given property. Return
	 *         <code>null</code>, if this property has no choice.
	 */
	public IChoice[] getChoices( String propName )
	{
		PropertyHandle propertyHandle = getPropertyHandle( propName );
		if ( propertyHandle == null )
			return null;
		return propertyHandle.getChoices( );
	}
	/**
	 * Returns the short display label for this element.