Created by: hinrik
ObjectSerializer::toHeaderValue() in the generated PHP code calls
toString() on the values, which formats JSON with the JSON_PRETTY_PRINT
option. This will result in a multi-line header which cannot be parsed
since linebreaks aren't allowed by RFC 7230.
In my case I have a header schema called UpdateUser which I had hoped
would be serialized as {"type":"staff","id":123}.
This PR adds a toHeaderValue() method to models which doesn't use JSON_PRETTY_PRINT. Works for me.
FYI @jebentier @dkarlovi @mandrean @jfastnacht @ackintosh @ybelenko @renepardon