[#4115] - Hardcoded string denies a customizable filename using JRPrintServiceExporter

As a developer, I want to fully set the name of the underlying PrintJob's name.
This way, I can manage the output filename of JRPrintServiceExporter#exportReport(), i.e., a printed document.

Unfortunately, there's a hardcoded line that always prepends"JasperReports - ".

See JRPrintServiceExporter, line 409 (version 5.6.0, also affecting up until 6.0.3):

printerJob.setJobName("JasperReports - " + jasperPrint.getName());