lib/classes/Variables.js/Variables/populateService
class Variables:  populateService(processedOptions) {
    this.options = processedOptions || {};

    this.loadVariableSyntax();

    const variableSyntaxProperty = this.service.provider.variableSyntax;

    // temporally remove variable syntax from service otherwise it'll match
    this.service.provider.variableSyntax = true;

    this.serverless.service.serverless = null;

    return this.populateObject(this.service).then(() => {
      this.service.provider.variableSyntax = variableSyntaxProperty;
      this.serverless.service.serverless = this.serverless;
      return BbPromise.resolve(this.service);
    });
  }