lib/classes/Service.js/Service/constructor
class Service:  constructor(serverless, data) {
    this.serverless = serverless;

    // Default properties
    this.service = null;
    this.provider = {};
    this.defaults = {
      stage: 'dev',
      region: 'us-east-1',
      variableSyntax: '\\${([ :a-zA-Z0-9._,\\-\\/\\(\\)]+?)}',
    };
    this.custom = {};
    this.plugins = [];
    this.functions = {};
    this.resources = {};
    this.package = {};

    if (data) this.update(data);
  }