Acceptance Criteria

• Deprecate all optional callback parameters (overloads) in public methods and emit a runtime warning when a callback is detected
  • Follow up with Shell to make sure it doesn't negatively affect them
• Provide access to a legacy client that allows callback use and does not emit these warnings
  • Ensure the legacy client has distinct metadata from the standard client for Atlas tracking
  • Release the client as a separate node module so that we can get npm statistics
  • Legacy client should depend on the main driver and expose wrapped methods that are able to handle callbacks
  • Do not introduce new error classes, use existing node driver error types

Implementation Requirements

• Deprecate callback signatures in all public methods: 
  • Exceptions are withSession and withTransaction (since they are specifically designed to use a callback)
  • Refer to the following draft design doc: Technical Design: Async Await inside the driver
  • Update the document by checking the compiled library for function method signatures and the src code for `callback?` and `cb?`

Testing Requirements

• For ease of maintenance, use a github-only pipeline with unit tests that cover the rewrapped methods:
  • callback form
    • happy path & error forwarding
  • promise form
    • happy path & error forwarding

Documentation Requirements

• API docs can be minimal and refer to main driver docs instead
• Readme for the legacy driver should briefly explain the purpose and give an example use
• MongoDB docs page should be updated with the deprecation notice for callbacks and point to the legacy driver for callback use