> We could introduce this in Jaybird 2.3 as an optional default

(requiring a

> Java system property to enable it).

That is a no-op.
Why would anyone do it?

Those who know and care are already fixing encoding in URL.
Those who do not know - they would not know about that change too.
Those who do not care... they do not care.

> Jaybird 3.0 we switch this around:

Magic of ".0" numbers...

It took 4 years to shift from 2.1.6 to 2.2.0 and don't know how many to move 2.1.0 to 2.2.0

You are not Mozilla, incrementing version each x months.
I do not expect even 2.3 anytime soon.
And 3.0 sounds like postponing to forever.