lib/classes/PluginManager.js/PluginManager/loadServicePlugins
class PluginManager:  loadServicePlugins(servicePlugs) {
    const servicePlugins = Array.isArray(servicePlugs) ? servicePlugs : [];

    // eslint-disable-next-line no-underscore-dangle
    module.paths = Module._nodeModulePaths(process.cwd());

    // we want to load plugins installed locally in the service
    if (this.serverless && this.serverless.config && this.serverless.config.servicePath) {
      module.paths.unshift(path.join(this.serverless.config.servicePath, '.serverless_plugins'));
    }

    this.loadPlugins(servicePlugins);
  }