lib/plugins/aws/package/compile/events/s3/index.js/AwsCompileS3Events/constructor
class AwsCompileS3Events:  constructor(serverless, options) {
    this.serverless = serverless;
    this.options = options;
    this.provider = this.serverless.getProvider('aws');

    this.hooks = {
      'package:compileEvents': () => {
        return BbPromise.bind(this)
          .then(this.newS3Buckets)
          .then(this.existingS3Buckets);
      },
    };
  }