I am working on filtering a Google Sheet for data and creating time series charts off of it with each athlete as a different series on the graph. The graph is being created properly but I cannot figure out how to set the legend labels on the graph using the built in functions.

function teamTimeSeriesChart(sportTeamSheet) {
    // Remove any existing charts
    var charts = sportTeamSheet.getCharts();
    charts.forEach(function(chart) {
        sportTeamSheet.removeChart(chart);
    });
    
    // Define the metrics to create charts for
    var metrics = [
        { column: 4, name: 'Stress Level' },
        { column: 5, name: 'Sleep Quality' },
        { column: 6, name: 'Sleep Duration' },
        { column: 7, name: 'Soreness Level' },
        { column: 8, name: 'Hydration Level' },
        { column: 9, name: 'Fueling Level' },
    ];

    // Get the number of rows
    var numRows = sportTeamSheet.getLastRow() - 1; // Subtract 1 to exclude header

    // Get date range
    var dateRange = sportTeamSheet.getRange(2, 1, numRows, 1); // Dates are in the first column

    // Get athlete names
    var athleteNameRange = sportTeamSheet.getRange(2, 2, numRows, 1);
    var athleteNames = athleteNameRange.getValues().flat().map(function(name) {
        return name.trim().toLowerCase();
    });

    // Create a set of unique athlete names
    var uniqueAthleteNames = Array.from(new Set(athleteNames));


    var generatedCharts = [];

    // Iterate over each metric
    metrics.forEach(function(metric) {
        // Create a new chart for the current metric
        var chartBuilder = sportTeamSheet.newChart();

        // Add date range
        chartBuilder.addRange(dateRange);
        Logger.log("Date range added: " + dateRange.getA1Notation());

        // Add a series for each unique athlete
        uniqueAthleteNames.forEach(function(name) {
            // Filter rows for the current athlete
            var athleteRows = [];
            for (var i = 0; i < numRows; i++) {
                if (athleteNames[i] === name) {
                    athleteRows.push(i + 1);
                }
            }


            if (athleteRows.length > 0) {
                // Create a continuous range for the current athlete's data for the current metric
                var startRow = athleteRows[0];
                var endRow = athleteRows[athleteRows.length - 1];
                var athleteDataRange = sportTeamSheet.getRange(startRow, metric.column, endRow - startRow + 1);

                // Add the series to the chart    
                chartBuilder.addRange(athleteDataRange);
                  
            }
        });
      

        // Build and insert the chart
        var chart = chartBuilder
            .setChartType(Charts.ChartType.LINE)
            .setOption('title', metric.name + ' Over Time')
            .setOption('hAxis', {
                title: 'Date',
                format: 'MM/dd/yyyy'
            })
            .setOption('vAxis', { title: 'Values (on scale of 1-10)' })
            .setPosition(2, 11 * generatedCharts.length + 1, 0, 0)
            .build();

        generatedCharts.push(chart);
    });

    return generatedCharts;
}

I have tried using .setOption and using labels, but it’s not working. It would be great if anyone could help.