Use Case

As a... Driver Engineer
I want... the MongoClient constructor to warn about, but accept keys with no values from connection string options if the keys are not an array option (i.e., readPreferenceTags)
So that... we will improve our spec compliance.

Currently the MongoClient constructor throws an error when provided a connection string where one or more options is provided an empty string:

mongodb://localhost:27017/?key0=&key1=someString

The spec expects that the options would be parsed to this option object:

{
  key0: '',
  key1: 'someString'
}

Also note that when parsing the connection string, the spec considers the key to include the first '='. i.e. this would not be valid according to the spec.

mongodb://localhost:27017/?key0&key1=someString

This is not accurate: https://github.com/mongodb/specifications/blob/master/source/connection-string/connection-string-spec.md#key-value-pair

User Impact

• Users will receive a warning, not an error, if they provide a URI with k-v pair with no value.
   

  Dependencies

• TBD based on answers to unknowns

Unknowns

• how would this change affect shell?

Acceptance Criteria

Implementation Requirements

• Remove logic that throws when encountering keys with empty string values from connection string if the key is not an array option
• Add logic to to emit a warning when encountering keys with empty string values if the key is not an array option

Testing Requirements

• Pull in spec tests that test for this behaviour

Documentation Requirements

• DOCSP ticket should be generated.
• Add example to release notes

Follow Up Requirements

• N/A