Add velocity ArgumentExtension

velocity/src/main/kotlin/org/anvilpowered/anvil/velocity/user/ArgumentExtensions.kt

@@ -0,0 +1,25 @@
+/*
+ *   Anvil - AnvilPowered.org
+ *   Copyright (C) 2019-2023 Contributors
+ *
+ *     This program is free software: you can redistribute it and/or modify
+ *     it under the terms of the GNU Affero General Public License as published by
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ *
+ *     This program is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU Affero General Public License for more details.
+ *
+ *     You should have received a copy of the GNU Affero General Public License
+ *     along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.anvilpowered.anvil.velocity.user
+
+import com.velocitypowered.api.command.CommandSource
+import org.anvilpowered.kbrig.builder.ArgumentBuilder
+
+fun <B : ArgumentBuilder<CommandSource, B>> B.requiresPermission(permission: String): B =
+    requires { it.hasPermission(permission) }