I use the OpenWeatherMap - alerts driver and it works. It's on Hubitat package manager:
OpenWeatherMap-Alerts-Weather-Driver - 
Custom Apps and Drivers / Custom Drivers - Hubitat
Now, I see in your log entry it is hitting the 2.5 API from openweathermap. Have you tried the 3.0? I have had problems in the past where it took a while for the API key to take a while to activate, but that would show up with a different error, not a Java error.