8209003: Consolidate use of empty collections in java.lang.module

Reviewed-by: alanb, mchung

src/java.base/share/classes/java/lang/module/ModuleFinder.java

@@ -306,7 +306,7 @@ public interface ModuleFinder {
 
                 @Override
                 public Set<ModuleReference> findAll() {
-                    return Collections.emptySet();
+                    return Set.of();
                 }
             };
         }