code: @Deprecated
    public static TraceContextHolder wrap(TraceContext traceContext) {
      return (traceContext != null) ? new TraceContextHolder(traceContext) : TraceContextHolder.EMPTY;
    }
docs: Used by TracedParallelBatch where its used to wrap a TraceContext and puts it in the
  registry for the forked execution.  This is marked deprecated as we prefer not to
  expose details of the RatpackCurrentTraceContext implementation.
  
  @param traceContext a trace context.
  @return a holder for the trace context, which can be put into the registry.