code: @Nullable
    public LegStep upComingStep() {
      if (routeLeg().steps().size() - 1 > stepIndex()) {
        return routeLeg().steps().get(stepIndex() + 1);
      }
      return null;
    }
docs: Get the next/upcoming step immediately after the current step. If the user is on the last step
  on the last leg, this will return null since a next step doesn't exist.
  
  @return a {@link LegStep} representing the next step the user will be on.
  @since 0.1.0