Thanks a lot, I think, this will help a lot of (java) users, and makes the usage of PostgreSQL DB a way better!
I had yesterday an idea for a solution on java side. As we have already a preprocessing with a jdbc wrapper, for function and procedure calls (in/out parameters are not working with postgres jdbc), I'll added preprocessing for the parameters.
I'll search the statement for all question marks (?) that are not inside a comment (-- \n, /* */), not in quotes (" ") and not in strings (' '), check the parameter, if it is null, and replace the ? by null, and reduce the parameter list.
I can link the code if you want, as it is Apache License 2.0.