Finagle 6.27.0

New Features

• finagle-http: Support nacks between Finagle Http clients and servers. When a server fails
  with retryable exceptions (exceptions wrapped by Failure.rejected), it sends back a "Nack"
  response, i.e. 503 Response code with a new "finagle-http-nack" header. This allows clients
  to safely retry failed requests, and keep connections open. RB_ID=705948

Runtime Behavior Changes

• finagle-core: FailFast parameter renamed from onOrOff to enabled. RB_ID=720781
• finagle-core: When evaluating NameTree unions, return components of the union in Ok state rather
  than waiting for all components to be Ok. This enables resilience of unions when part of the
  tree cannot be resolved. RB_ID=697114
• finagle-stats: Standard of deviation is no longer calculated. It is exported as a constant 0.0
  for "$statName.stddev". RB_ID=717647

Breaking API Changes

• finagle-stream: Introduce StreamRequest as a replacement for Netty's
  HttpRequest, and converted the rest of the public API to not leak
  other Netty types (notably ChannelBuffer is replaced by Buf). RB_ID=695896
• finagle-core: Dtab does not implement the Namer interface anymore. Use
  c.t.f.naming.DefaultInterpreter to bind a name via a Dtab. Support for Dtab entries starting
  with /#/ has been removed. c.t.f.Namer.bindAndEval has been removed. Use
  c.t.f.Namer.resolve instead. RB_ID=711681
• finagle: LoadService and ThriftRichClient migrated off of deprecated ClassManifest
  to ClassTag. RB_ID=720455