Hello Christina,
I believe that's a Java access restriction from the Mendix cloud settings - If I remember this right, you need to raise it with Mendix if you need that to run on the cloud, as far as running locally you can either disable Cloud security emulation or add the permission in the relevant config.
I'll have a look for the config file - could you let me know if it works for you with cloud security emulation disabled?
(To disable it you need to open the project setting, open your active setting, and under the "Server" tab click "No" on "Emulate cloud security")
I'll add a comment below if I can find the file with the permission.