Sorry for the late response, hope you've figured it out by now, but if you haven't...it's been a while since I did this and I actually had to switch my app to 3.x as I was building it because 4.x is still missing some functionality I needed. I found this in my old code which has all the labels seen in my legend. Maybe that's what you need, to create a renderer with labels?
//Define the UniqueValueRenderer for displaying quail habitat status
var qhRenderer = {
type: "unique-value",
field: "OfficialQH",
legendOptions: { title: "Quail Habitat Status" },
uniqueValueInfos: [{
value: 0,
symbol: {
type: "simple-fill",
color: [225, 225, 225],
outline: {
color: "black",
width: 1
}
},
label: "Not Quail Habitat"
},
{
value: 1,
symbol: {
type: "simple-fill",
color: "green",
outline: {
color: "black",
width: 1
}
},
label: "Quail Habitat"
}]
};