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/command/ContentCommand.java
{
					if ( ( value instanceof StructRefValue )
							|| ( (ElementRefValue) value ).isResolved( ) )
					{
						try
						{
							
							
							PropertyCommand cmd = new PropertyCommand( module,
									element );
							cmd.setProperty( propDefn.getName( ), null );
						}
						catch ( SemanticException e )
						{
							assert false;
						}
					}
				}
			}
		}
	}
	/**
	 * Deletes user properties. This will also remove property values from this
	 * element and derived elements.
	 * 
	 * @param obj
	 *            the element to clean up
	 * @throws UserPropertyException
	 *             if an error occurs, but the operation should not fail under
	 *             normal conditions