Use Case

As a Node.js engineer
I want a consistent experience with types returned from the server 
So that logging and event monitoring is clear and accurate

The Monitor is configured to promoteBuffers, a setting that will change Binary types to Node.js Buffers. This makes the subtype inaccessible and degrades the log-ability and readability of the value. 

Mainly, this fixes a logging inconvenience, our hellos are longer than 1000 characters because we are hitting Buffer.prototype.toJSON instead of Binary’s extended JSON format

User Impact

• Depends on our opinion on the reply field of the serverHeartBeat event and how it relates to semver. Technically this field changes depending on the server version/topology you connect to.

Dependencies

• The "signature.hash" field

Unknowns

• Is there any code that depends on this change? The main focus is to make signature.hash a Binary again so that it will inspect as a base64 string. Are there other Binary fields the monitor may receive? Is there any reason they should not be Binary?

Acceptance Criteria

Implementation Requirements

• set promoteBuffers to false in monitor constructor
  • The "signature.hash" field should be a Binary

Testing Requirements

• assert the Monitor calls command with promoteBuffers set to false
• Manually verify that signature.hash is a Binary

Documentation Requirements

• API documentation on server reply fields and semver

Follow Up Requirements

• None