update to Gradle 9.2.0; always use Java 25 toolchain to generate javadoc

Notes:
- Gradle 9+ requires Java 17 to run
- using Java 21 on GitHub Actions
- not using Java 25 because Kotlin does not yet support it and output some warnings

.github/workflows/ci.yml

@@ -27,10 +27,10 @@ jobs:
 
       - uses: gradle/actions/wrapper-validation@v4
 
-      - name: Setup Java 11
+      - name: Setup Java 21
         uses: actions/setup-java@v4
         with:
-          java-version: 11
+          java-version: 21
           distribution: temurin  # pre-installed on ubuntu-latest
           cache: gradle
 
@@ -95,10 +95,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup Java 11
+      - name: Setup Java 21
         uses: actions/setup-java@v4
         with:
-          java-version: 11
+          java-version: 21
           distribution: temurin  # pre-installed on ubuntu-latest
           cache: gradle
 

.github/workflows/error-prone.yml

@@ -26,10 +26,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup Java 11
+      - name: Setup Java 21
         uses: actions/setup-java@v4
         with:
-          java-version: 11
+          java-version: 21
           distribution: temurin  # pre-installed on ubuntu-latest
           cache: gradle
 

.github/workflows/fonts.yml

@@ -34,10 +34,10 @@ jobs:
         steps:
             - uses: actions/checkout@v4
 
-            - name: Setup Java 11
+            - name: Setup Java 21
               uses: actions/setup-java@v4
               with:
-                  java-version: 11
+                  java-version: 21
                   distribution: temurin  # pre-installed on ubuntu-latest
                   cache: gradle
 

.github/workflows/natives.yml

@@ -58,10 +58,10 @@ jobs:
 #             if: matrix.os == 'ubuntu-latest'
 #             run: sudo apt-get install g++-aarch64-linux-gnu
 
-            - name: Setup Java 11
+            - name: Setup Java 21
               uses: actions/setup-java@v4
               with:
-                  java-version: 11
+                  java-version: 21
                   distribution: temurin
                   cache: gradle
 

.github/workflows/pr-snapshots.yml

@@ -21,10 +21,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - name: Setup Java 11
+      - name: Setup Java 21
         uses: actions/setup-java@v4
         with:
-          java-version: 11
+          java-version: 21
           distribution: temurin  # pre-installed on ubuntu-latest
           cache: gradle