Added @NestedCommand(executeBody=true/false) annotation.

Setting this annotation to true will execute the method
body of the tagged method if the argument count is 0.

src/main/java/com/sk89q/minecraft/util/commands/CommandsManager.java

@@ -456,7 +456,18 @@ public abstract class CommandsManager<T> {
 
         int argsCount = args.length - 1 - level;
 
-        if (method.isAnnotationPresent(NestedCommand.class)) {
+        // checks if we need to execute the body of the nested command method (false)
+        // or display the help what commands are available (true)
+        // this is all for an args count of 0 if it is > 0 and a NestedCommand Annotation is present
+        // it will always handle the methods that NestedCommand points to
+        // e.g.:
+        //  - /cmd - @NestedCommand(executeBody = true) will go into the else loop and execute code in that method
+        //  - /cmd <arg1> <arg2> - @NestedCommand(executeBody = true) will always go to the nested command class
+        //  - /cmd <arg1> - @NestedCommand(executeBody = false) will always go to the nested command class not matter the args
+        boolean executeNested = method.isAnnotationPresent(NestedCommand.class)
+                && (argsCount > 0 || !method.getAnnotation(NestedCommand.class).executeBody());
+
+        if (executeNested) {
             if (argsCount == 0) {
                 throw new MissingNestedCommandException("Sub-command required.",
                         getNestedUsage(args, level, method, player));

src/main/java/com/sk89q/minecraft/util/commands/NestedCommand.java

@@ -38,4 +38,9 @@ public @interface NestedCommand {
      * A list of classes with the child commands.
      */
     Class<?>[] value();
+
+    /**
+     * If set to true it will execute the body of the tagged method.
+     */
+    boolean executeBody() default false;
 }