[Feature] I'd like to make a legend according to the data links instead of data nodes in my graph

### What problem does this feature solve?

As title, in my graph, I'd like to make a legend according to the data links instead of data nodes. I couldn't find any parameter to achieve this.
Setting my data links value as a categories of legend, so I could click certain links value, and show all nodes connected by certain links.

this is my data link as below:
"nodes":[...]
"links":[
0:{
"source":"JIO1"
"target":"UPD6"
"value":[
0:"data flow (low speed)"
]
"lineStyle":{
"color":"lightblue"
}
"label":{
"show":true
"fontSize":10
"formatter":"{c}"
}
},
1:{
"source":"JIO1"
"target":"UPD4"
"value":[
0:"control flow"
]
"lineStyle":{
"color":"thistle"
}
"label":{
"show":true
"fontSize":10
"formatter":"{c}"
}
}........

### What does the proposed API look like?

I'm not sure.
maybe, legend > Style =links > .........