Did you have a read through the SDK documentation?
IReportLogon (SAP BusinessObjects Business Intelligence Platform Java SDK)
Report report = (IReport) reports.get(i);
IReportProcessingInfo pluginInterface = (IReportProcessingInfo)
report.getPluginProcessingInterface("CrystalReport");
ISDKList dbLogons = pluginInterface.getReportLogons();
More about this code here: Display and modify database logon information for a report
Hope this helps,
Josh