SimpleMemberMap became internal between 1.42 and 1.50.2

[richardissimo]

We've just updated our NuGet package from 1.42 to 1.50.2, and at some point in between those two, SimpleMemberMap has become internal (a breaking change). I can't spot anything on the release notes mentioning this. Please can someone suggest how to create one of these, or what the new way of creating a SqlMapper.IMemberMap is? We were using it like this...

_customMappedMembers[nameToMap] = new SimpleMemberMap(nameToMap, _type.GetProperty(member.Name));

and

 _customMappedMembers[nameToMap] = new SimpleMemberMap(nameToMap, _type.GetField(member.Name));