Option 1 – If you want to use your Jar in a several reports.
You should “Add Jar” (as it called in iReport repository manager) to some folder in the Jasper Server folder tree. Then “Add reference” to this resource in Resources section of you specific report.
Option 2 – You need a jar in a specific report.
Use “Add Jar” option in a resources section of specific report.
Worked perfectly on JasperServer 4.7