Commands should return an int success count

src/main/java/com/mojang/brigadier/Command.java

@@ -2,6 +2,9 @@ package com.mojang.brigadier;
 
 import com.mojang.brigadier.context.CommandContext;
 
+@FunctionalInterface
 public interface Command<S> {
-    void run(CommandContext<S> context);
+    int SINGLE_SUCCESS = 1;
+
+    int run(CommandContext<S> context);
 }

src/main/java/com/mojang/brigadier/CommandDispatcher.java

@@ -39,9 +39,9 @@ public class CommandDispatcher<S> {
         root.addChild(command.build());
     }
 
-    public void execute(String command, S source) throws CommandException {
+    public int execute(String command, S source) throws CommandException {
         CommandContext<S> context = parseNodes(root, command, new CommandContextBuilder<>(source));
-        context.getCommand().run(context);
+        return context.getCommand().run(context);
     }
 
     private CommandContext<S> parseNodes(CommandNode<S> node, String command, CommandContextBuilder<S> contextBuilder) throws CommandException {

src/main/java/com/mojang/brigadier/builder/ArgumentBuilder.java

@@ -7,7 +7,7 @@ import com.mojang.brigadier.tree.RootCommandNode;
 import java.util.Collection;
 import java.util.function.Predicate;
 
-public abstract class ArgumentBuilder<S, T extends ArgumentBuilder<S, ?>> {
+public abstract class ArgumentBuilder<S, T extends ArgumentBuilder<S, T>> {
     private final RootCommandNode<S> arguments = new RootCommandNode<>();
     private Command<S> command;
     private Predicate<S> requirement = s -> true;