Allow plus symbol in maven package version

So people can upload maven package with version like 1.0+debian64
Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

ee/changelogs/unreleased/dz-allow-plus-in-version.yml

+---
+title: Allow plus symbol in maven package version
+merge_request: 9657
+author:
+type: fixed

ee/lib/ee/gitlab/regex.rb

@@ -20,7 +20,7 @@ module EE
       end
 
       def maven_path_regex
-        package_name_regex
+        @maven_path_regex ||= %r{\A\@?(([\w\-\.]*)/)*([\w\-\.\+]*)\z}.freeze
       end
 
       def maven_app_name_regex

ee/spec/lib/gitlab/regex_spec.rb

@@ -33,4 +33,21 @@ describe Gitlab::Regex do
     it { is_expected.not_to match('my package name') }
     it { is_expected.not_to match('!!()()') }
   end
+
+  describe '.maven_path_regex' do
+    subject { described_class.maven_path_regex }
+
+    it { is_expected.to match('123') }
+    it { is_expected.to match('foo') }
+    it { is_expected.to match('foo/bar') }
+    it { is_expected.to match('@foo/bar') }
+    it { is_expected.to match('com/mycompany/app/my-app') }
+    it { is_expected.to match('com/mycompany/app/my-app/1.0-SNAPSHOT') }
+    it { is_expected.to match('com/mycompany/app/my-app/1.0-SNAPSHOT+debian64') }
+    it { is_expected.not_to match('com/mycompany/app/my+app/1.0-SNAPSHOT') }
+    it { is_expected.not_to match('$foo/bar') }
+    it { is_expected.not_to match('@foo/@/bar') }
+    it { is_expected.not_to match('my package name') }
+    it { is_expected.not_to match('!!()()') }
+  end
 end