Expose list of all artifacts, including transitive

And add support for :type and :classifier in defs.bzl:artifact() by internally
using strip_packaging_and_classifier_and_version. To keep support for groupId:artifactId
update strip_packaging_and_classifier_and_version implementation for that case.

To be used like
    load("@maven//:defs.bzl", "maven_artifacts")

and for example
    load("@rules_jvm_external//:defs.bzl", "artifact")
    load("@rules_jvm_external//:specs.bzl", "parse")

    all_maven_targets = [artifact(a) for a in maven_artifacts if not parse.parse_maven_coordinate(a).get("classifier", "compile") in ["sources", "native"]]

    java_export(
        name = "maven-transitive-deps-lib",
        maven_coordinates = "com.example.deps:%s:%s" % (name, "0.1"),
        visibility = ["//visibility:public"],
        runtime_deps = all_maven_targets,
    )

which makes "maven-transitive-deps-lib-pom" target available that
can be useful for other tools like security scanners and/or dependabot

coursier.bzl

@@ -15,7 +15,7 @@ load("//third_party/bazel_json/lib:json_parser.bzl", _json_parse = "json_parse")
 load("//private/rules:jetifier.bzl", "jetify_artifact_dependencies", "jetify_maven_coord")
 load("//:specs.bzl", "maven", "parse", "utils")
 load("//private:artifact_utilities.bzl", "deduplicate_and_sort_artifacts")
-load("//private:coursier_utilities.bzl", "SUPPORTED_PACKAGING_TYPES", "escape")
+load("//private:coursier_utilities.bzl", "SUPPORTED_PACKAGING_TYPES", "escape", "strip_packaging_and_classifier")
 load("//private:dependency_tree_parser.bzl", "JETIFY_INCLUDE_LIST_JETIFY_ALL", "parser")
 load("//private:java_utilities.bzl", "parse_java_version")
 load("//private:proxy.bzl", "get_java_proxy_args")
@@ -471,11 +471,13 @@ def _pinned_coursier_fetch_impl(repository_ctx):
         "load(\"@bazel_tools//tools/build_defs/repo:utils.bzl\", \"maybe\")",
         "def pinned_maven_install():",
     ]
+    maven_artifacts = []
     netrc_entries = {}
 
     for artifact in dep_tree["dependencies"]:
         if artifact.get("url") != None:
             http_file_repository_name = escape(artifact["coord"])
+            maven_artifacts.extend([artifact["coord"]])
             http_files.extend([
                 "    http_file(",
                 "        name = \"%s\"," % http_file_repository_name,
@@ -499,6 +501,8 @@ def _pinned_coursier_fetch_impl(repository_ctx):
 
     http_files.extend(_get_jq_http_files())
 
+    http_files.extend(["maven_artifacts = [\n%s\n]" % (",\n".join(["    \"%s\"" % artifact for artifact in maven_artifacts]))])
+
     repository_ctx.file("defs.bzl", "\n".join(http_files), executable = False)
     repository_ctx.file(
         "netrc",

private/coursier_utilities.bzl

@@ -46,6 +46,10 @@ def strip_packaging_and_classifier(coord):
     return ":".join(coordinates)
 
 def strip_packaging_and_classifier_and_version(coord):
+    coordinates = coord.split(":")
+    # Support for simplified versionless groupId:artifactId coordinate format
+    if len(coordinates) == 2:
+        return ":".join(coordinates)
     return ":".join(strip_packaging_and_classifier(coord).split(":")[:-1])
 
 # TODO: Should these methods be combined with _parse_maven_coordinate_string in specs.

private/rules/artifact.bzl

@@ -1,19 +1,17 @@
 load("//:specs.bzl", "parse")
 load("//private:constants.bzl", "DEFAULT_REPOSITORY_NAME")
+load("//private:coursier_utilities.bzl", "strip_packaging_and_classifier_and_version")
 
 def artifact(a, repository_name = DEFAULT_REPOSITORY_NAME):
-    artifact_obj = _parse_artifact_str(a) if type(a) == "string" else a
-    return "@%s//:%s" % (repository_name, _escape(artifact_obj["group"] + ":" + artifact_obj["artifact"]))
+    artifact_str = _make_artifact_str(a) if type(a) != "string" else a
+    return "@%s//:%s" % (repository_name, _escape(strip_packaging_and_classifier_and_version(artifact_str)))
 
 def maven_artifact(a):
     return artifact(a, repository_name = DEFAULT_REPOSITORY_NAME)
 
 def _escape(string):
     return string.replace(".", "_").replace("-", "_").replace(":", "_")
 
-def _parse_artifact_str(artifact_str):
-    pieces = artifact_str.split(":")
-    if len(pieces) == 2:
-        return {"group": pieces[0], "artifact": pieces[1]}
-    else:
-        return parse.parse_maven_coordinate(artifact_str)
+def _make_artifact_str(artifact_obj):
+    # TODO: add support for optional type, classifier and version parts in artifact_obj case
+    return artifact_obj["group"] + ":" + artifact_obj["artifact"]