The source connector generates a (schemaless) payload based on a database collection.

All document data types work as one would expect, except Int64.

A MongoDb document field 'level' of data type Int32 is translated into 

"level": 3

That looks good. Now, when the data type of field 'level' is Int64, the output is 

"level":

{    "$numberLong": "3" }

The nested $numberLong element and the number represented as a string/varchar indicate a bug? I'd expect just "level": 3 to be the output again.

When sinking data into a collection, the default MongoDb data type for integers is Int64. Sourcing from the same collection results in this unexpected output.

Bug or expected though mysterious behavior?