[JENKINS-68699] Upgrade Yarn from 1.22.19 to 3.2.0 (#5824)

Co-authored-by: Basil Crow <me@basilcrow.com>

.gitattributes

@@ -38,3 +38,7 @@
 *.png           binary
 *.war           binary
 *.zip           binary
+
+# Yarn
+# https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
+/war/.yarn/plugins/** binary

war/.gitignore

@@ -2,6 +2,15 @@ work
 /rebel.xml
 junit.xml
 
+# Yarn
+# https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/sdks
+!.yarn/versions
+
 # Node
 node/
 node_modules/

war/.yarnrc.yml

@@ -0,0 +1,8 @@
+# Defines what linker should be used for installing Node packages (useful to
+# enable the node-modules plugin), one of: pnp, pnpm and node-modules.
+nodeLinker: node-modules
+
+# The yarnPath setting is currently the preferred way to install Yarn within a
+# project, as it ensures that your whole team will use the exact same Yarn
+# version, without having to individually keep it up-to-date.
+yarnPath: .yarn/releases/yarn-3.2.0.cjs

war/pom.xml

@@ -47,7 +47,11 @@ THE SOFTWARE.
     <!-- HTTP listener port -->
     <port>8080</port>
     <node.version>16.15.1</node.version>
+    <!-- frontend-maven-plugin will install this Yarn version as bootstrap, then hand over control to Yarn Berry. -->
     <yarn.version>1.22.19</yarn.version>
+    <!-- maven-antrun-plugin will download this Yarn version. -->
+    <yarn-berry.version>3.2.0</yarn-berry.version>
+    <yarn-berry.sha256sum>99a7f42f678b8ccd9c8e97a9e65fe7a5043033dd0e074e6d1f13fbe2d5ff2734</yarn-berry.sha256sum>
   </properties>
 
   <dependencyManagement>
@@ -696,6 +700,32 @@ THE SOFTWARE.
               </execution>
             </executions>
           </plugin>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-antrun-plugin</artifactId>
+            <executions>
+              <execution>
+                <id>download-yarn</id>
+                <goals>
+                  <goal>run</goal>
+                </goals>
+                <phase>initialize</phase>
+                <configuration>
+                  <tasks>
+                    <property name="yarn.dest" value="${project.basedir}/.yarn/releases/yarn-${yarn-berry.version}.cjs" />
+                    <dirname file="${yarn.dest}" property="yarn.dest.dir" />
+                    <mkdir dir="${yarn.dest.dir}" />
+                    <get dest="${yarn.dest}" src="https://repo.yarnpkg.com/${yarn-berry.version}/packages/yarnpkg-cli/bin/yarn.js" usetimestamp="true" />
+                    <checksum algorithm="SHA-256" file="${yarn.dest}" property="${yarn-berry.sha256sum}" verifyProperty="yarn.checksum.matches" />
+                    <condition property="yarn.checksum.matches.fail">
+                      <equals arg1="${yarn.checksum.matches}" arg2="false" />
+                    </condition>
+                    <fail if="yarn.checksum.matches.fail">Checksum error</fail>
+                  </tasks>
+                </configuration>
+              </execution>
+            </executions>
+          </plugin>
           <plugin>
             <groupId>com.github.eirslett</groupId>
             <artifactId>frontend-maven-plugin</artifactId>
@@ -722,11 +752,6 @@ THE SOFTWARE.
                   <goal>yarn</goal>
                 </goals>
                 <phase>initialize</phase>
-                <configuration>
-                  <!-- ensure only one concurrent 'yarn install' -->
-                  <!-- when yarn cache is empty, multiple yarns performing network fetches frequently results in opaque errors -->
-                  <arguments>--mutex network</arguments>
-                </configuration>
               </execution>
 
               <execution>