public boolean sessionExistsInFileSystem(long sessionId) {
        return Files.exists(Paths.get(tenantFileSystemDirs.sessionsPath().getAbsolutePath(), String.valueOf(sessionId)));
    }
Returns application data for the given application.
Returns Optional.empty if application not found or no application data exists.
configserver/src/main/java/com/yahoo/vespa/config/server/application/TenantApplications.java