Supported collection types

[mariussoutier]

When I use Seq or Array, I get the following error:

java.lang.UnsupportedOperationException: Could not generate schema. Cannot support yet: Seq[String]

With List, it seems to work. Please document which collection types are supported, and if possible support Seq as well.

[julianpeeters]

Sorry you ran into this, and thanks for the feedback.

Avro array is represented by List[T], and I've made that a little more clear in the readme.

Telling @AvroTypeProvider which collection type to generate is going to be ugly (can only pass one string literal into a macro), but I'll see what I can do.

[mariussoutier]

@AvroTypeProvider could generate Seq instead of List to be more generic? Otherwise it doesn't really matter for generated code. So documenting which types work with @AvroRecord should be enough for now.