Allow ConfigurationKey values up to 1000 chars

[andig]

Fix evcc-io/evcc#12901

Seems there are boxes sending >500 characters...

[lorenzodonini]

This does go against the spec (just to quote you on this topic #240 (comment)).
Then again this change would be harmless, until it remains constrained to configuration values, so that vendors can pass enormous JSON files in custom config 😅

To accept this, the unit test needs to be fixed accordingly though.

[andig]

Agreed regarding spec. Workaround is to not use getConfiguration in the case. Retracting, thank you!

[premultiply]

Workaround is to not use getConfiguration in the case.

That might be an expensive workaround. Even not usable in some cases.

I think it would be fine to accepting the double size of each value inside getConfiguration items for improved compatibility.