unused_deps is a command line tool to determine any unused dependencies in java_library rules. targets.  It outputs buildozer commands to apply the suggested prunings.
Build a binary and put it into your $GOPATH/bin:
go install github.com/bazelbuild/buildtools/unused_deps@latest
unused_deps TARGET...
Here, TARGET is a space-separated list of Bazel labels, with support for :all and ...