This was obtained by setting up this environment:
guix shell -D guix --with-input=guile@3.0.9=guile-next \
--with-commit=guile-next=e2ed33ef0445c867fe56c247054aa67e834861f2
-- make -j5
then adding 'unused-module' to (@@ (guix build compiler) %warnings),
building, and checking all the "unused module" warnings and removing
those that were definitely unused.
* guix/build/clojure-build-system.scm (compile-java): New variable.
(build): Copy classes compiled from Java and optionally Java sources to
the final jar.
(%standard-phases): Add compile-java phase before build.
* guix/build/clojure-utils.scm (%java-source-dirs): New variable.
(%java-compile-dir): New variable.
* guix/build-system/clojure.scm (clojure-build): Include %java-source-dirs and
%java-compile-dir.
(builder): Include %java-source-dirs and %java-compile-dir.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>