@Documented
@Retention(value=RUNTIME)
@Target(value=TYPE)
public static @interface CssResource.Shared

Indicates that the String accessor methods defined in a CssResource will return the same values across all implementations of that type.

This is an example of "stateful" class selectors being used:

@Shared
 interface FocusCss extends CssResource {
   String focused();
   String unfocused();
 }
 
 interface PanelCss extends CssResource, FocusCss {
   String widget();
 }
 
 interface InputCss extends CssResource, FocusCss {
   String widget();
 }
 
 input.css:
 *.focused .widget {border: thin solid blue;}
 
 Application.java:
 myPanel.add(myInputWidget);
 myPanel.addStyleName(instanceOfPanelCss.focused());
 

Because the FocusCss interface is tagged with @Shared, the focused() method on the instance of PanelCss will match the .focused parent selector in input.css.

The effect of inheriting an Shared interface can be replicated by use use of the CssResource.Import annotation (e.g. .FocusCss-focused .widget), however the use of state-bearing descendant selectors is common enough to warrant an easier use-case.