Support JDK v21+ only (#1920)

Author: gavinbunney

.github/workflows/benchmark.yml

@@ -7,7 +7,7 @@ permissions:
   contents: read
 
 env:
-  JDK: '17'
+  JDK: '21'
   DISTRIBUTION: 'zulu'
   GRADLE_COMMAND: './gradlew --no-daemon'
 

.github/workflows/branch_snapshot.yml

@@ -32,7 +32,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
           cache: 'gradle'
       - name: Build snapshot
         run: ./gradlew build snapshot -Prelease.version="$BUILD_VERSION"

.github/workflows/pr.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [17, 21]
+        java: [21]
     steps:
       - uses: actions/checkout@v4
         with:

.github/workflows/release.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
           cache: 'gradle'
       - name: Build candidate
         if: contains(github.ref, '-rc.')

.github/workflows/snapshot.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: 17
+          java-version: 21
           cache: 'gradle'
       - name: Build snapshot
         run: ./gradlew build snapshot

build.gradle

@@ -18,7 +18,7 @@ ext.githubProjectName = rootProject.name
 
 idea {
     project {
-        languageLevel = '17'
+        languageLevel = '21'
     }
 }
 
@@ -67,12 +67,12 @@ subprojects {
 
     group = "com.netflix.${githubProjectName}"
 
-    sourceCompatibility = '17'
-    targetCompatibility = '17'
+    sourceCompatibility = '21'
+    targetCompatibility = '21'
 
     java {
         toolchain {
-            languageVersion = JavaLanguageVersion.of(17)
+            languageVersion = JavaLanguageVersion.of(21)
         }
     }