Simplify Argument for common use cases

Add Executor to SWCommand

SpigotCore_Main/src/de/steamwar/command/Argument.java

@@ -33,6 +33,7 @@ public class Argument<T> {
     public static final Argument<Long> LONG = new Argument<>(ArgumentType.LONG, l -> true);
     public static final Argument<Float> FLOAT = new Argument<>(ArgumentType.FLOAT, integer -> true);
     public static final Argument<Double> DOUBLE = new Argument<>(ArgumentType.DOUBLE, integer -> true);
+    public static final Argument<String> STRING = new Argument<>(ArgumentType.STRING, string -> true);
     public static final Argument<String> PLAYER = new Argument<>(ArgumentType.STRING, string -> Bukkit.getPlayer(string) == null, Bukkit::getPlayer);
 
     private ArgumentType<T> argumentType;

SpigotCore_Main/src/de/steamwar/command/SWCommand.java

@@ -32,6 +32,7 @@ public class SWCommand {
 
     public SWCommand(Executor executor, Argument<?>... arguments) {
         this.arguments = arguments;
+        this.executor = executor;
     }
 
     public boolean checkValidity(String[] args) {
@@ -40,7 +41,7 @@ public class SWCommand {
         }
         for (int i = 0; i < args.length; i++) {
             Optional<?> optional = arguments[i].valueSupplier(args[i]);
-            if (optional.isEmpty()) return false;
+            if (!optional.isPresent()) return false;
         }
         return true;
     }
@@ -51,7 +52,9 @@ public class SWCommand {
         }
         Object[] objects = new Object[args.length];
         for (int i = 0; i < args.length; i++) {
-            objects[i] = arguments[i].valueSupplier(args[i]).orElseThrow();
+            Optional<?> optional = arguments[i].valueSupplier(args[i]);
+            if (!optional.isPresent()) throw new IllegalStateException();
+            objects[i] = optional.get();
         }
         return Optional.of(executor.execute(player, objects));
     }