[http-client] Exception Mapper/Async Retry

[SentryMan]

Fixes that long-standing async retry capability gap and adds exception mapping for requests

• now can configure a global exception mapper that maps HttpException to other kinds of exception
• can set error handlers on a per-request basis to override the global mapper
• Modify generator to read throws statement on Client interfaces, if the Exception has a constructor that accepts HttpException, an error mapper will auto generate for the request
• Async Requests now propagate connection errors as HttpException matching sync behavior
• Async requests can now use retry handlers
• upgrade to prisms 1.12

@Client
interface ApiClient {

  @Get("/mapped")
  String mapped(@Header("Accept") String accept) throws MappedException;
}
class MappedException extends RuntimeException {

  public MappedException(HttpException e) {}
}

The following impl method will generate

  // GET /mapped
  @Override
  public String mapped(String accept) {
    return client.request()
      .header("Accept", accept)
      .path("mapped")
      .errorMapper(MappedException::new)
      .GET()
      .asPlainString().body();
  }

fixes #273

[rbygrave]

This errorMapper.apply() isn't where I was expecting it to be.

I was thinking it would be part of checkMaybeThrow() ... so I'm pondering this. This does not look right in that we want to let the response be decoded if necessary and HttpException is thrown later?

I'll pull this and see how it works and why it's not what I was expecting - looks cool otherwise.

[SentryMan]

This is so it'll work for connection exceptions

[SentryMan]

Hmm, wait you might be right

[rbygrave]

Yeah, we need the mapping to occur also in the checkResponse() and checkMaybeThrow() (as well as in the sendWith())

See the additional commits at: #275

[rbygrave]

Awesome work btw !!!