<p>
     * The urls in UIDL message may use Vaadin specific protocol. Before
     * actually using the urls on the client side, they should be passed via
     * {@link com.vaadin.client.ApplicationConnection#translateVaadinUri(String)}.
     * <p>
     * Note that in current terminal implementation StreamVariables are cleaned
     * from the terminal only when:
     * <ul>
     * <li>a StreamVariable with same name replaces an old one
     * <li>the variable owner is no more attached
     * <li>the developer signals this by calling
     * {@link StreamingStartEvent#disposeStreamVariable()}
     * </ul>
     * Most commonly a component developer can just ignore this issue, but with
     * strict memory requirements and lots of StreamVariables implementations
     * that reserve a lot of memory this may be a critical issue.
<p>
     * The urls in UIDL message may use Vaadin specific protocol. Before
     * actually using the urls on the client side, they should be passed via
     * {@link com.vaadin.client.ApplicationConnection#translateVaadinUri(String)}.
     * <p>
     * Note that in current terminal implementation StreamVariables are cleaned
     * from the terminal only when:
     * <ul>
     * <li>a StreamVariable with same name replaces an old one
     * <li>the variable owner is no more attached
     * <li>the developer signals this by calling
     * {@link StreamingStartEvent#disposeStreamVariable()}
     * </ul>
     * Most commonly a component developer can just ignore this issue, but with
     * strict memory requirements and lots of StreamVariables implementations
     * that reserve a lot of memory this may be a critical issue. | PaintTarget.java