lib/classes/PluginManager.js/PluginManager/loadCommand
class PluginManager:  loadCommand(pluginName, details, key) {
    const commands = _.mapValues(details.commands, (subDetails, subKey) =>
      this.loadCommand(pluginName, subDetails, `${key}:${subKey}`)
    );
    return _.assign({}, details, { key, pluginName, commands });
  }