Overwriting Read method %Stream.FileCharacter class returns incorrect return type at compile time

When overwriting the Read method (that has a %CacheString return type) on a new class that inherits %Stream.FileCharacter class, returns an error about incorrect return type, must be Binary, even if it matched the real signature.

Looking at the compile global information we can see:

^oddCOM("%Stream.FileBinary","m","Read",42)="%Library.Binary"

After further investigation we realise that there is a generator method looking at the OdbcType class definition.

Setting LONGVARCHAR results in:

^oddCOM("User.CStream","m","Read",42)="%Library.String"