Invocable Apex that can be called from a Flow to detect and translate text using the Google Translate API

This is a simple Apex class that sends an HTTP request to the Google Cloud Translation API that can be found here: https://cloud.google.com/translate/docs/reference/rest/v2/translate

This was created to address a repeated problem I've seen in my time consulting in the public sector -- when serving a diverse user base, as is common in the public sector, oftentimes data entered by external users is entered in a language that is not readable by the organization's internal users. By implementing this class with a record triggered flow on the troublesome data, you can save your users a small headache.

This bulk of this class is an invokable method that is designed to be called from an asynchronous path of a record triggered flow, for easy configuration and implementation by Salesforce admins. Trigger the flow however you see fit, call the action while passing it the appropriate parameters, receive the translation, and then do whatever database actions you need to do to store the translation (in the original field, in a different field, etc). See the below image for a basic example.

Please note, if you do not want to call this method from an asynchronous path, you will need to add an @Future annotation to the translate method, and perform an update to your desired field within the method itself.

This class uses a Google API Service Account for authentication. Christian Szandor Knapp has an excellent tutorial here: https://www.salesforceben.com/google-api-and-service-accounts-get-up-and-running-in-30-minutes/

Please note that in TranslateCallout.cls there are some variables that should instead be stored in custom metadata for production use.

I've also provided test coverage up to 96% for TranslateCallout.cls. Unfortunately, at the time of writing this, there is no actual supported way to provide real test coverage for the JWTBearerTokenExchange class (used here in the getAccessToken() method). As a result, in order to provide test coverage, an "interesting" use case of !Test.isRunningTest() is included in the getAccessToken() method.