Define ".setSeriesNames" as a specific column from my Feature Collection when charting in GEE

Question

I have an asset imported from a shapefile in GEE. It is a feature collection with which I wish to chart a time series. The lines from each feature are labelled as system:index. See labelling of picture below and ignore the amount of features, it's a WIP.

I want them to be labelled as the "fid" column in my asset's table. See picture below (column to the right).

Can this be done with .setSeriesNames or some other argument?

Code for chart is the usual, found below.

//// Plot results
var chart = ui.Chart.image.seriesByRegion(
  s2CloudMasked, 
  fc,
  ee.Reducer.median(),
  'NDVI',10)
  .setChartType('LineChart')
  .setSeriesNames([])
  .setOptions({
    interpolateNulls: true,
    lineWidth: 1,
    pointSize: 3,
    title: 'NDVI monthly G3',
    hAxis: {title: 'Date'},
    vAxis: {title: 'NDVI'},
    series: {0:{color: 'red'}
    }
  });
print(chart)

Answer 1

Turns out I only needed to specify the seriesProperty parameter as "fid":

var chart = ui.Chart.image.seriesByRegion({
  imageCollection: s2CloudMasked,
  band: 'NDVI',
  regions: fc,
  reducer: ee.Reducer.median(),
  seriesProperty: 'fid',
})

Answer 2

Assuming that 'fid' is unique for each feature, you can simply assign it to the system:index on each feature and it'll get used as the series label. But to do that you have to convert the collection to a list (so that system:index isn't assigned by the collection) and back. You may or may not also need to convert the fid to a string (using ee.Number.format)

fc = ee.FeatureCollection(fc.toList(100).map(function(f) {
  f = ee.Feature(f)
  return f.set("system:index", f.get('fid'))
}))