Get plugin commands

file.php

<?php
array_unique(array_map(function ($command) {
  /** @var Command $command */
  return $command->getName();
}, array_filter($cmds = $this->getServer()->getCommandMap()->getCommands(), function ($command) use($plugin, $cmds) {
  /** @var Command $command */
  return $command instanceof PluginIdentifiableCommand and $command->getPlugin() === $plugin or isset($cmds[strtolower($plugin->getName() . ":" . $command->getName())]);
})));