Debian 11 user here. Apt install gradle, and git cloned bitcoinj as instructed. And then in bash...:
$ gradle run --args="dump decrypt --dump-privkeys --wallet="/path/to/schildbach/wallet""
... yields the message:
FAILURE: Build failed with an exception.
* What went wrong:
Problem configuring task :bitcoinj-tools:run from command line.
> Unknown command-line option '--args'.
... has anybody got a fix for the --args= problem please?