• Add W3C TraceContext codec/propagation (#694, @pavolloffay)
• Configuration do not cache sender instance (#685, @ehsavoie)
• Prevent a shutdown hook from being removed in JaegerTracer when a shutdown is in progress (#689, @TomasHofman)
• Fix ThriftSender max span size check (#670, @yhpark)
• Unregister shutdown hook when tracer is closed (#679, @TomasHofman)