GetIndexes is currently returning a value of type IEnumerable<BsonDocument>, requiring the caller to know the structure of the returned BsonDocuments and to write code to decode them. Most commands return type safe result types that have methods and properties that safely decode the results for the caller. GetIndexes should return a value of type GetIndexesResult, which would allow users to access the results of GetIndexes in a type safe manner and with assistance from Intellisense.

This is a backward breaking change. Maybe it could be made non-breaking in some way (for example by having GetIndexesResult derive from IEnumerable<BsonDocument>, which we normally wouldn't do).