Header parameters only support limited character set

[uschi2000]

The conjure spec does not define how arbitrary data be encoded for transport in HTTP headers; in contrast, percent encoding per https://tools.ietf.org/html/rfc3986 covers such encoding for path and query parameters. Consequently, conjure header parameters currently only support parameters over a restricted character set.

Illustration: https://github.com/palantir/conjure-java-runtime/pull/1068 Further reading: https://dzone.com/articles/utf-8-in-http-headers