gradle-ssh-plugin | Gradle SSH Plugin provides SSH facilities such as command | Plugin library

I think your problem is that you are piping the input to the screen command and not actually to the java process. I would do it the following way:

1. create a file with your input, something along the lines of echo "foo" > input.txt
2. scp that file to the machine
3. run the screen command and make the java process either read the file directly (if that program can do that) or pipe it properly by running a bash command instead of the java command directly. Something along the lines of screen -dmS screen-name bash \"cat input.txt | java -jar ...\"

Disclaimer: the above escaping is just approximate to get my point accorss ;-)