Sometimes when attempting to create a threshold in an existing threshold group, clicking Save results in "OpenNMS Web User Interface Has Experienced an Error."

It seems to happen more frequently than not, and occurs intermittently even when attempting to create a threshold with the same values. It does not seem to matter what type of threshold is selected, or which fields are left blank.

In the jetty-server.log, we see "Index X out of bounds for length X", where X is the number of currently configured thresholds. When inspecting the form field payload in Chrome, we see isNew: true and thresholdIndex: X, where X is the number of currently configured thresholds.