Add worldsOfType to WorldManager.

Just a handy shortcut for plugin developers who want to get all worlds
of a type quick and easy.

Signed-off-by: Chris Sanders <[email protected]>

Author: Zidane

src/main/java/org/spongepowered/api/world/server/WorldManager.java

@@ -26,6 +26,7 @@
 
 import org.spongepowered.api.ResourceKey;
 import org.spongepowered.api.Server;
+import org.spongepowered.api.world.WorldType;
 import org.spongepowered.api.world.server.storage.ServerWorldProperties;
 
 import java.nio.file.Path;
@@ -130,6 +131,13 @@ default List<ResourceKey> offlineWorldKeys() {
      */
     Optional<ResourceKey> worldKey(UUID uniqueId);
 
+    /**
+     * Retrieves all {@link ServerWorld worlds} that are of a particular {@link WorldType type}.
+     * @param type The type
+     * @return The {@link Collection worlds}
+     */
+    Collection<ServerWorld> worldsOfType(WorldType type);
+
     /**
      * Loads a {@link ServerWorld world} from a {@link WorldTemplate template}.
      *