The documentation of `DuplicateKeyException` states:

> Subclass of WriteConcernException representing a duplicate key exception

And `WriteConcernException` in turn:

> An exception representing an error reported due to a write failure.

This is confusing. From the documentation one has to assume that `DuplicateKeyException` is thrown in case a duplicate key is encountered during a write operation.
What's actually thrown is a `MongoCommandException` with `ErrorCategory.fromErrorCode(e.code) == ErrorCategory.DUPLICATE_KEY`.

The documentation of `DuplicateKeyException` should be amended to clarify that it's not actually used (in certain situations) in this case counter to what the developer may expect or assume.