Require minimum JDK 11 in line with MapStruct Core. (#48)

Author: Chessray

.github/workflows/gradle.yml

@@ -18,10 +18,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 1.8
+    - name: Set up JDK 11
       uses: actions/setup-java@v1
       with:
-        java-version: 1.8
+        java-version: 11
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
     - name: Build with Gradle

build.gradle

@@ -48,7 +48,7 @@ subprojects {
 
     java {
         toolchain {
-            languageVersion.set(JavaLanguageVersion.of(8))
+            languageVersion.set(JavaLanguageVersion.of(11))
         }
     }