code: static TracezZPageHandler create(
        @javax.annotation.Nullable RunningSpanStore runningSpanStore,
        @javax.annotation.Nullable SampledSpanStore sampledSpanStore) {
      return new TracezZPageHandler(runningSpanStore, sampledSpanStore);
    }
docs: Constructs a new {@code TracezZPageHandler}.
  
  @param runningSpanStore the instance of the {@code RunningSpanStore} to be used.
  @param sampledSpanStore the instance of the {@code SampledSpanStore} to be used.
  @return a new {@code TracezZPageHandler}.