in inject/inject-utils/src/main/scala/com/twitter/inject/utils/ExceptionUtils.scala [86:91]
def isNonRetryable(t: Throwable): Boolean = t match {
case _: NonRetryableException => true
case f: FailureFlags[_] if f.isFlagged(FailureFlags.Ignorable) => true
case f: Failure if f.cause.isDefined => isNonRetryable(f.cause.get)
case _ => false
}