This is one implementation of the [Builder Pattern](https://en.wikipedia.org/wiki/Builder_pattern) in the Ruby programming language. This is primarily used for composing objects to transport a set of data to a receiver with a specific payload. The advantage of using a builder over a plain Hash is using explicit methods to set required fields, and getting a common way to present your data to the receiver. By default, `.build` will transform your data into a hash, but you can override this method to create your preferred format.