I am using Google Apps Script and EmbeddedChartBuilder to embed line charts within my Google Spreadsheet. When you create these charts by hand, you have the (non-default) option to "Use column A as labels" (where "A" is the first column in the data range). I cannot find a way to do the same from a script. From the Google Visualization Line Chart documentation, it appears that the default is to treat the first column as having the "domain" role; but EmbeddedChartBuilder seems to override this and give all columns the "data" role. Since I don't have an explicit DataTable, I have no way to set the column roles myself.
Have I missed a way to do this? Or do I have to switch approaches from EmbeddedChartBuilder to using the spreadsheet as a data source?