In some versions of Jaspersoft Studio, Groovy scripting language jar file needs to be updated, as the one supplied with Jaspersoft is not always compatible with the BP formatter scriptlet. If during report compilation an error appears complaining of JRScriptletException class missing, a Groovy library matching the version used in Jaspersoft studio plugins folder must be downloaded from the official groovy distribution (use groovy-all-X.X.X.jar from "embedded" subfolder). The official groovy jar has to be renamed to have exact same name as the supplied groovy jar, as it uses "_" instead of "-" in the name.
JasperStudio uses Java8 to start, and does not start when this is removed:
C:\Users\username\Desktop\TIBCO\Jaspersoft Studio\7.9.0\jaspersoftstudiopro\features\jre.win32.win32.x86_64.feature_1.8.0.u151
Tibco Jaspersoft Studio 6.10.0 Download