Add Override annotations where appropriate

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/material/Command.java

@@ -30,6 +30,7 @@ public class Command extends MaterialData implements Redstone {
      *
      * @return true if powered, otherwise false
      */
+    @Override
     public boolean isPowered() {
         return (getData() & 1) != 0;
     }