nix: stop downloading POMs for Clojure dependencies

Clojure dependencies require only JARs to work. Downloading POMs is both
a waste of time, space, and bandwidth. In addition POMs create edge
cases that we would have to handle, an would rather avoid.

For example, the `guice` package which shows up in the classpath
includes a JAR named `guice-4.2.2-no_aop.jar`. The issue with that is
that there is no corresponding POM in the directory:
https://repo1.maven.org/maven2/com/google/inject/guice/4.2.2/

Either we have to make a special case for such packages, or we can just
skip POMs entirely and avoid the mess.

Signed-off-by: Jakub Sokołowski <jakub@status.im>

nix/deps/clojure/README.md

@@ -12,12 +12,13 @@ By using the following command:
 ```sh
 shadow-cljs classpath --force-spawn
 ```
-We both download the necessary JARs and POMs into `~/.m2` folder, but also get the classpath printed into standard output.
+We download the necessary JARs into `~/.m2` folder, but also get the classpath printed into standard output.
+We skip POM files since they are not necessary, and add edge cases we don't want to handle.
 
 We then use the classpath in combination with contents of `~/.m2` folder to generate the following files:
 
 * `deps.list` - List of JARs relative to the `~/.m2` cache folder.
-* `deps.json` - Full list of JARs and POMs including their SHAs.
+* `deps.json` - Full list of JARs including their SHAs.
 
 The `deps.list` file is just intermediate and for debugging purposes.
 The `deps.json` is loaded by the derivation in [`default.nix`](./default.nix) and used to produce a derivation that contains all the necessary dependencies:

nix/deps/clojure/default.nix

@@ -8,9 +8,6 @@ let
   # load dependencies
   deps = importJSON ./deps.json;
 
-  # some .jar files have an `-aot` suffix that doesn't work for .pom files
-  getPOM = jarUrl: "${removeSuffix "-aot" jarUrl}.pom";
-
   script = writeShellScriptBin "create-local-maven-repo" (''
     mkdir -p $out
     cd $out
@@ -18,18 +15,11 @@ let
   (concatMapStrings (dep: 
     let
       url = "${dep.host}/${dep.path}";
-      pom = {
-        sha1 = attrByPath [ "pom" "sha1" ] "" dep;
-        sha256 = attrByPath [ "pom" "sha256" ] "" dep;
-      };
-      pom-download = optionalString (pom.sha256 != "") (
-        fetchurl { url = getPOM url; inherit (pom) sha256; }
-      );
       jar = {
         sha1 = attrByPath [ "jar" "sha1" ] "" dep;
         sha256 = attrByPath [ "jar" "sha256" ] "" dep;
       };
-      jar-download = optionalString (jar.sha256 != "") (
+      jarFile = optionalString (jar.sha256 != "") (
         fetchurl { url = "${url}.jar"; inherit (jar) sha256; }
       );
       fileName = last (splitString "/" dep.path);
@@ -38,14 +28,8 @@ let
       ''
         mkdir -p ${directory}
 
-        ${optionalString (pom-download != "") ''
-        ln -s "${pom-download}" "${getPOM dep.path}"
-        ''}
-        ${optionalString (pom.sha1 != "") ''
-        echo "${pom.sha1}" > "${getPOM dep.path}.sha1"
-        ''}
-        ${optionalString (jar-download != "") ''
-        ln -s "${jar-download}" "${dep.path}.jar"
+        ${optionalString (jarFile != "") ''
+        ln -s "${jarFile}" "${dep.path}.jar"
         ''}
         ${optionalString (jar.sha1 != "") ''
         echo "${jar.sha1}" > "${dep.path}.jar.sha1"

nix/deps/clojure/generate.sh

@@ -53,8 +53,6 @@ function nix_entry_from_jar() {
     JAR_PATH="${MAVEN_CACHE_PATH}/${JAR_REL_PATH}"
     JAR_NAME=$(basename "${JAR_PATH}")
     JAR_DIR=$(dirname "${JAR_PATH}")
-    # POM might have a slightly different name
-    POM_PATH=$(echo ${JAR_DIR}/*.pom)
 
     REPO_NAME=$(get_repo_for_dir "${JAR_DIR}")
     REPO_URL=${REPOS[${REPO_NAME}]}
@@ -62,18 +60,11 @@ function nix_entry_from_jar() {
     JAR_SHA1=$(cat "${JAR_PATH}.sha1")
     JAR_SHA256=$(get_nix_sha "${JAR_PATH}")
 
-    POM_SHA1=$(cat "${POM_PATH}.sha1")
-    POM_SHA256=$(get_nix_sha "${POM_PATH}")
-    
     # Format into a Nix attrset entry
     echo -n "
   {
     \"path\": \"${JAR_REL_NAME}\",
     \"host\": \"${REPO_URL}\",
-    \"pom\": {
-      \"sha1\": \"${POM_SHA1}\",
-      \"sha256\": \"${POM_SHA256}\"
-    },
     \"jar\": {
       \"sha1\": \"${JAR_SHA1}\",
       \"sha256\": \"${JAR_SHA256}\"