This function is called after toReportDF (or the overriding.toDF if it is specified) in order to transform the basic data.frame into the form that will appear in the report. This typically includes transforming columns into links, adding image columns, etc. Each class publishable by ReportingTools should have either a custom objectToHTML method (which supercedes toReportDF and modifyReportDF) or a custom toReportDF and modifyReportDF methods which construct a dataframe to be placed in the report as an HTML table.
signature(df = "ANY", htmlRep = "ANY", object = "ANY")
The default method is simply a placeholder, and returns the data.frame unchanged.