https://mongodb.github.io/mongo-csharp-driver/2.8/apidocs/html/P_MongoDB_Bson_IO_IByteBuffer_Capacity.htm
IByteBuffer.Capacity Property
capacityproperty
https://mongodb.github.io/mongo-csharp-driver/2.8/apidocs/html/M_MongoDB_Bson_LazyBsonDocument__ctor.htm
LazyBsonDocument Constructor (IByteBuffer)
Initializes a new instance of the class.
constructor