When clustering, provide control over what gets shown in the legend

[wayfaringrob]

I have a feature class that I'd like to turn on clustering for, but I don't want this in my legend:

Granted, my feature service doesn't have that many features in it, and the values may become sensible when more are added, but I really don't need the range shown in my legend at all. I have the clusters labeled; the symbol would be identifiable if there were just one icon in the legend like a single symbol layer:

Allow the user to choose whether their clustered symbols show up in the legend.