Remove Java 11 from CI matrix, use only Java 17

Co-authored-by: Mte90 <403283+Mte90@users.noreply.github.com>

Author: Copilot

.github/workflows/kotlin-ci.yml

@@ -8,25 +8,22 @@ on:
 
 jobs:
   build-kotlin-plugin:
-    name: 'Build (matrix: Java ${{ matrix.java-version }})'
+    name: 'Build (Java 17)'
     runs-on: ubuntu-latest
     permissions:
       contents: read
-    strategy:
-      matrix:
-        java-version: [11, 17]
 
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - name: Set up JDK ${{ matrix.java-version }}
+      - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: ${{ matrix.java-version }}
+          java-version: 17
 
       - name: Cache Gradle
         uses: actions/cache@v4
@@ -35,9 +32,9 @@ jobs:
             ~/.gradle/caches
             ~/.gradle/wrapper
             ide-plugins/.gradle
-          key: gradle-${{ matrix.java-version }}-${{ hashFiles('ide-plugins/**/*.gradle*','ide-plugins/**/gradle-wrapper.properties') }}
+          key: gradle-17-${{ hashFiles('ide-plugins/**/*.gradle*','ide-plugins/**/gradle-wrapper.properties') }}
           restore-keys: |
-            gradle-${{ matrix.java-version }}-
+            gradle-17-
 
       - name: Setup Gradle wrapper if missing
         run: |
@@ -66,7 +63,7 @@ jobs:
       - name: Upload diagnostics
         uses: actions/upload-artifact@v4
         with:
-          name: ci-diagnostics-java-${{ matrix.java-version }}
+          name: ci-diagnostics
           path: out/ci-diagnostics.txt
 
       - name: Full build with stacktrace (capture to file)
@@ -79,7 +76,7 @@ jobs:
       - name: Upload build log
         uses: actions/upload-artifact@v4
         with:
-          name: gradle-build-log-java-${{ matrix.java-version }}
+          name: gradle-build-log
           path: gradle-build.log
 
       - name: Build Kotlin plugin subproject if present
@@ -101,7 +98,7 @@ jobs:
       - name: Upload kotlin-subproject/build logs if present
         uses: actions/upload-artifact@v4
         with:
-          name: kotlin-subproject-logs-java-${{ matrix.java-version }}
+          name: kotlin-subproject-logs
           path: |
             kotlin-subproject-build.log
             assemble.log