Through the User Interface, you can make changes to an Atom's properties through Manage->Atom Management->Properties. You can modify properties such as Purge History, as well as Heap Size. However, despite there appearing to be no blank values, the following error may pop up once the update message has been sent: Oops, an unexpected error has occurred. Boomi has been notified of the issue. Values must be non-empty.
Most likely, this issue is because within the Custom Atom Properties, one of the System or Container Properties are left blank. Once you remove this property and click save, the Atom restart message should pop up through the interface.
If this does not resolve the issue, there may be a permission error, and you should try to modify these properties directly through the container.properties file. If the issue still persists, raise a support case to address this concern.