Work on a couple of the todos

dicore3/command/src/main/java/io/dico/dicore/command/ChildCommandAddress.java

@@ -1,5 +1,6 @@
 package io.dico.dicore.command;
 
+import io.dico.dicore.command.predef.DefaultGroupCommand;
 import io.dico.dicore.command.predef.HelpCommand;
 
 import java.util.*;
@@ -23,7 +24,7 @@ public class ChildCommandAddress extends ModifiableCommandAddress {
     }
 
     public static ChildCommandAddress newPlaceHolderCommand(String name, String... aliases) {
-        ChildCommandAddress rv = new ChildCommandAddress(null, name, aliases);
+        ChildCommandAddress rv = new ChildCommandAddress(DefaultGroupCommand.getInstance(), name, aliases);
         HelpCommand.registerAsChild(rv);
         return rv;
     }

dicore3/command/src/main/java/io/dico/dicore/command/CommandBuilder.java

@@ -210,15 +210,39 @@ public final class CommandBuilder {
      * @param shortDescription a short description
      * @param description      the lines of a full description.
      * @return this
+     * @throws IllegalStateException if the current group has no command
      */
     public CommandBuilder setGroupDescription(String shortDescription, String... description) {
         Command command = cur.getCommand();
+        if (command == null) throw new IllegalStateException();
         cur.setCommand(command
                 .setShortDescription(shortDescription)
                 .setDescription(description));
         return this;
     }
 
+    /**
+     * Add a context filter to the command of the current group
+     * @return this
+     * @throws IllegalStateException if the current group has no command
+     */
+    public CommandBuilder addContextFilter(IContextFilter contextFilter) {
+        Command command = cur.getCommand();
+        if (command == null) throw new IllegalStateException();
+        cur.setCommand(command
+            .addContextFilter(contextFilter));
+        return this;
+    }
+
+    /**
+     * Add a required permission to the command of the current group
+     * @return this
+     * @throws IllegalStateException if the current group has no command
+     */
+    public CommandBuilder addRequiredPermission(String permission) {
+        return addContextFilter(IContextFilter.permission(permission));
+    }
+
     /**
      * Jump up a level in the address
      *

dicore3/command/src/main/java/io/dico/dicore/command/ModifiableCommandAddress.java

@@ -2,6 +2,7 @@ package io.dico.dicore.command;
 
 import io.dico.dicore.command.chat.ChatControllers;
 import io.dico.dicore.command.chat.IChatController;
+import io.dico.dicore.command.predef.DefaultGroupCommand;
 import io.dico.dicore.command.predef.HelpCommand;
 import io.dico.dicore.command.predef.PredefinedCommand;
 
@@ -32,7 +33,7 @@ public abstract class ModifiableCommandAddress implements ICommandAddress {
     @Override
     public boolean hasUserDeclaredCommand() {
         Command command = getCommand();
-        return command != null && !(command instanceof PredefinedCommand);
+        return command != null && !(command instanceof PredefinedCommand) && !(command instanceof DefaultGroupCommand);
     }
 
     @Override

dicore3/command/src/main/java/io/dico/dicore/command/RootCommandAddress.java

@@ -1,6 +1,7 @@
 package io.dico.dicore.command;
 
 import io.dico.dicore.command.parameter.ArgumentBuffer;
+import io.dico.dicore.command.predef.DefaultGroupCommand;
 import io.dico.dicore.command.registration.BukkitCommand;
 import org.bukkit.Location;
 import org.bukkit.command.CommandSender;
@@ -167,10 +168,10 @@ public class RootCommandAddress extends ModifiableCommandAddress implements ICom
         ModifiableCommandAddress targetAddress = getCommandTarget(sender, buffer);
         Command target = targetAddress.getCommand();
 
-        if (target == null) {
+        if (target == null || target instanceof DefaultGroupCommand) {
             if (targetAddress.hasHelpCommand()) {
                 target = targetAddress.getHelpCommand().getCommand();
-            } else {
+            } else if (target == null){
                 return false;
             }
         }

dicore3/command/src/main/java/io/dico/dicore/command/annotation/RequirePermissions.java

@@ -7,6 +7,9 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+/**
+ * If this annotation is not present, inheriting permissions is default.
+ */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.METHOD)
 public @interface RequirePermissions {

dicore3/command/src/main/java/io/dico/dicore/command/predef/DefaultGroupCommand.java

@@ -0,0 +1,24 @@
+package io.dico.dicore.command.predef;
+
+import io.dico.dicore.command.Command;
+import io.dico.dicore.command.CommandException;
+import io.dico.dicore.command.ExecutionContext;
+import org.bukkit.command.CommandSender;
+
+public class DefaultGroupCommand extends Command {
+    private static final DefaultGroupCommand instance = new DefaultGroupCommand();
+
+    public static DefaultGroupCommand getInstance() {
+        return instance;
+    }
+
+    private DefaultGroupCommand() {
+
+    }
+
+    @Override public String execute(CommandSender sender, ExecutionContext context) throws CommandException {
+        context.getAddress().getChatController().sendHelpMessage(sender, context, context.getAddress(), 1);
+        return null;
+    }
+
+}