Split out monlithic derivation into multiple files

pkgs/development/python-modules/skein/skeinrepo.nix

@@ -0,0 +1,46 @@
+{ autoPatchelfHook, lib, maven, stdenv, src, version }:
+
+stdenv.mkDerivation rec {
+  name = "skein-${version}-maven-repo";
+
+  inherit src;
+
+  nativeBuildInputs = [ maven ] ++ lib.optional stdenv.isLinux autoPatchelfHook;
+
+  doBuild = false;
+
+  installPhase = ''
+    mkdir -p $out
+
+    archs="${
+      if stdenv.isLinux
+      then "linux-x86_32 linux-x86_64"
+      else "osx-x86_64"
+    }"
+
+    for arch in $archs
+    do
+      mvn -Dmaven.repo.local=$out dependency:get -Dartifact=com.google.protobuf:protoc:3.0.0:exe:$arch
+      mvn -Dmaven.repo.local=$out dependency:get -Dartifact=io.grpc:protoc-gen-grpc-java:1.16.0:exe:$arch
+    done
+
+    if ${ lib.boolToString stdenv.isLinux }
+    then
+      autoPatchelf $out
+    fi
+
+    # We have to use maven package here as dependency:go-offline doesn't
+    # fetch every required jar.
+    mvn -f java/pom.xml -Dmaven.repo.local=$out package
+
+    rm $(find $out -name _remote.repositories)
+    rm $(find $out -name resolver-status.properties)
+  '';
+
+  outputHashMode = "recursive";
+  outputHashAlgo = "sha256";
+  outputHash = if stdenv.isLinux
+    then "12f0q3444qw6y4f6qsa9540a0fz4cgi844zzi8z1phqn3k4dnl6v"
+    else "0bjbwiv17cary1isxca0m2hsvgs1i5fh18z247h1hky73lnhbrz8";
+
+} // lib.optionalAttrs stdenv.isLinux { dontAutoPatchelf = true; }