Add JDK 21 to CI

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         scala: [2.12.18]
-        java: [temurin@8, temurin@11, temurin@17]
+        java: [temurin@8, temurin@11, temurin@17, temurin@21]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Ignore line ending differences in git
@@ -69,6 +69,14 @@ jobs:
           java-version: 17
           cache: sbt
 
+      - name: Setup Java (temurin@21)
+        if: matrix.java == 'temurin@21'
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+          cache: sbt
+
       - name: Check that workflows are up to date
         shell: bash
         run: sbt '++ ${{ matrix.scala }}' githubWorkflowCheck
@@ -138,6 +146,14 @@ jobs:
           java-version: 17
           cache: sbt
 
+      - name: Setup Java (temurin@21)
+        if: matrix.java == 'temurin@21'
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+          cache: sbt
+
       - name: Download target directories (2.12.18)
         uses: actions/download-artifact@v4
         with:

build.sbt

@@ -45,7 +45,8 @@ ThisBuild / githubWorkflowOSes := Seq("ubuntu-latest", "macos-latest", "windows-
 ThisBuild / githubWorkflowJavaVersions := Seq(
   JavaSpec.temurin("8"),
   JavaSpec.temurin("11"),
-  JavaSpec.temurin("17")
+  JavaSpec.temurin("17"),
+  JavaSpec.temurin("21")
 )
 
 name := "sbt-osgi"