Merge branch 'sh-update-plantutml-gem' into 'master'

Update asciidoctor-plantuml gem to v0.0.12

See merge request gitlab-org/gitlab!32376

Gemfile

@@ -148,7 +148,7 @@ gem 'creole', '~> 0.5.0'
 gem 'wikicloth', '0.8.1'
 gem 'asciidoctor', '~> 2.0.10'
 gem 'asciidoctor-include-ext', '~> 0.3.1', require: false
-gem 'asciidoctor-plantuml', '0.0.10'
+gem 'asciidoctor-plantuml', '~> 0.0.12'
 gem 'rouge', '~> 3.19.0'
 gem 'truncato', '~> 0.7.11'
 gem 'bootstrap_form', '~> 4.2.0'

Gemfile.lock

@@ -84,7 +84,7 @@ GEM
     asciidoctor (2.0.10)
     asciidoctor-include-ext (0.3.1)
       asciidoctor (>= 1.5.6, < 3.0.0)
-    asciidoctor-plantuml (0.0.10)
+    asciidoctor-plantuml (0.0.12)
       asciidoctor (>= 1.5.6, < 3.0.0)
     ast (2.4.0)
     atlassian-jwt (0.2.0)
@@ -1162,7 +1162,7 @@ DEPENDENCIES
   asana (~> 0.9)
   asciidoctor (~> 2.0.10)
   asciidoctor-include-ext (~> 0.3.1)
-  asciidoctor-plantuml (= 0.0.10)
+  asciidoctor-plantuml (~> 0.0.12)
   atlassian-jwt (~> 0.2.0)
   attr_encrypted (~> 3.1.0)
   awesome_print

changelogs/unreleased/sh-update-plantutml-gem.yml

+---
+title: Update asciidoctor-plantuml gem to v0.0.12
+merge_request: 32376
+author:
+type: other

doc/administration/integration/plantuml.md

@@ -115,6 +115,19 @@ that, login with an Admin account and do following:
 - Check **Enable PlantUML** checkbox.
 - Set the PlantUML instance as `https://gitlab.example.com/-/plantuml/`.
 
+NOTE: **Note:** If you are using a PlantUML server running v1.2020.9 and
+above (for example, [plantuml.com](https://plantuml.com)), set the `PLANTUML_ENCODING`
+environment variable to enable the `deflate` compression. On Omnibus,
+this can be done set in `/etc/gitlab.rb`:
+
+```ruby
+gitlab_rails['env'] = { 'PLANTUML_ENCODING' => 'deflate' }
+```
+
+From GitLab 13.1 and later, PlantUML integration now
+[requires a header prefix in the URL](https://github.com/plantuml/plantuml/issues/117#issuecomment-6235450160)
+to distinguish different encoding types.
+
 ## Creating Diagrams
 
 With PlantUML integration enabled and configured, we can start adding diagrams to