move plusone provider and aspect to separate file

scala/plusone.bzl

@@ -0,0 +1,12 @@
+PlusOneDeps = provider(
+    fields = {
+        'direct_deps' : 'list of direct compile dependencies of a target',
+    }
+)
+
+def _collect_plus_one_deps_aspect_impl(target, ctx):
+    return [PlusOneDeps(direct_deps = getattr(ctx.rule.attr,'deps',[]))]
+
+collect_plus_one_deps_aspect = aspect(implementation = _collect_plus_one_deps_aspect_impl,
+    attr_aspects = ['deps'],
+)

scala/private/common.bzl

@@ -1,4 +1,5 @@
 load("@io_bazel_rules_scala//scala:jars_to_labels.bzl", "JarsToLabelsInfo")
+load("@io_bazel_rules_scala//scala:plusone.bzl", "PlusOneDeps")
 
 def write_manifest(ctx):
     main_class = getattr(ctx.attr, "main_class", None)
@@ -157,16 +158,3 @@ def create_java_provider(scalaattr, transitive_compile_time_jars):
         ),
         transitive_runtime_jars = scalaattr.transitive_runtime_jars,
     )
-
-PlusOneDeps = provider(
-    fields = {
-        'direct_deps' : 'list of direct compile dependencies of a target',
-    }
-)
-
-def _collect_plus_one_deps_aspect_impl(target, ctx):
-    return [PlusOneDeps(direct_deps = getattr(ctx.rule.attr,'deps',[]))]
-
-collect_plus_one_deps_aspect = aspect(implementation = _collect_plus_one_deps_aspect_impl,
-    attr_aspects = ['deps'],
-)

scala/scala.bzl

@@ -25,7 +25,7 @@ load(
     _specs2_junit_dependencies = "specs2_junit_dependencies",
 )
 load(
-    "@io_bazel_rules_scala//scala/private:common.bzl",
+    "@io_bazel_rules_scala//scala:plusone.bzl",
     _collect_plus_one_deps_aspect = "collect_plus_one_deps_aspect",
 )