Stackoverflow when mapping using NEST

[sljohtmboe]

I'm encountering a stackoverflow when using NEST to map classes which contain an IEnumerable of the same class.

I've created a test which fails demonstrating the problem.

The problem appears to be in the WriteProperties method (in Nest.Resolvers.Writers.TypeMappingWriter.cs). The deepType is added to the dictionary of seenTypes, however when newTypeMappingWriter is created using the internal constructor it's _type member is set to the result of GetUnderlyingType(deepType) the _type member is then used to check the seenTypes which returns 0 as the underlying type (in the case of an array or a generic) never make it into seenTypes.

I've reproduced the error in 1.0.0-beta1 and latest master (9612928).

[gmarz]

@sljohtmboe thanks for finding this and creating a test to reproduce 👍. The issue was that we were adding the collection type to seenTypes instead of the underlying type itself.