code: private static <A, B> Consumer3<FusionTraceContext, Promise<A>, Settable<B>> adaptToAcceptTraceContext(
        final PromisePropagator<A, B> propagator) {
      return (traceContext, src, dest) -> propagator.accept(src, dest);
    }
docs: Drops FusionTraceContext on the floor. This method adapts pure transformation to be used within FusionTask
  that needs additional information (FusionTraceContext) to build trace.