Enable using @Stylesheet with vaadin:// (#9934)

Change-Id: I895fad31ef5b31a395cea95e64d6b183d718056f

client/src/com/vaadin/client/ApplicationConnection.java

@@ -2940,6 +2940,14 @@ public class ApplicationConnection {
                 uidlUri = serviceUrl + relativeUrl;
             }
         }
+        if (uidlUri.startsWith(ApplicationConstants.VAADIN_PROTOCOL_PREFIX)) {
+            final String vaadinUri = configuration.getVaadinDirUrl();
+            String relativeUrl = uidlUri
+                    .substring(ApplicationConstants.VAADIN_PROTOCOL_PREFIX
+                            .length());
+            uidlUri = vaadinUri + relativeUrl;
+        }
+
         return uidlUri;
     }
 

server/src/com/vaadin/annotations/StyleSheet.java

@@ -32,6 +32,11 @@ import com.vaadin.server.ClientConnector;
  * Relative urls are mapped to APP/PUBLISHED/[url] which are by default served
  * from the classpath relative to the class where the annotation is defined.
  * <p>
+ * Special Vaadin urls are also supported. The most useful is vaadin:// which
+ * maps to the location of the automatically published VAADIN folder. Using the
+ * VAADIN folder and vaadin:// you can publish stylesheets which use images or
+ * other files with relative paths.
+ * <p>
  * Example: {@code @StyleSheet( "http://host.com/file1.css", "file2.css"})} on
  * the class com.example.MyConnector would load the file
  * http://host.com/file1.css as is and file2.css from /com/example/file2.css on

shared/src/com/vaadin/shared/ApplicationConstants.java

@@ -34,6 +34,7 @@ public class ApplicationConstants implements Serializable {
             + "PUBLISHED";
 
     public static final String APP_PROTOCOL_PREFIX = "app://";
+    public static final String VAADIN_PROTOCOL_PREFIX = "vaadin://";
     public static final String PUBLISHED_PROTOCOL_NAME = "published";
     public static final String PUBLISHED_PROTOCOL_PREFIX = PUBLISHED_PROTOCOL_NAME
             + "://";