Update workflow and build to Java 17

Author: leonard84

.github/workflows/main.yml

@@ -16,7 +16,7 @@ jobs:
       - name: 'Set up JDK'
         uses: actions/setup-java@v5
         with:
-          java-version: 8
+          java-version: 17
           distribution: temurin
       - name: Init Gradle Build Action
         uses: gradle/actions/setup-gradle@v5
@@ -38,7 +38,7 @@ jobs:
       - name: 'Set up JDK'
         uses: actions/setup-java@v5
         with:
-          java-version: 8
+          java-version: 17
           distribution: temurin
       - name: 'Check Spock'
         run: |
@@ -57,7 +57,7 @@ jobs:
       - name: 'Set up JDK'
         uses: actions/setup-java@v5
         with:
-          java-version: 8
+          java-version: 17
           distribution: temurin
       - name: 'Check Spock'
         run: |

README.adoc

@@ -14,12 +14,17 @@ All builds (Gradle and Maven) will automatically download all required dependenc
 
 === Prerequisites
 
-- JDK 8 or higher
+- JDK 17 or higher
 - Maven use `mvnw` wrapper
 - Gradle use `gradlew` wrapper
 
 NOTE: This example shows the usage of Spock 2.0, which uses the JUnit Platform. If you want to see how to get Spock 1.x with JUnit 4 up and running see the https://github.com/spockframework/spock-example/tree/spock-1.x[Spock-1.x] Branch.
 
+NOTE: Spock supports Java 8, but Groovy 5.0 requires Java 11+ and Gradle 9+ requires Java 17+.
+      So for simplicity’s sake the example uses Java 17.
+      If you want to use an older Java version, please use an older Gradle version (e.g. Gradle 8.x for Java 8+).
+     Check the https://github.com/spockframework/spock-example/tree/java-8[Java-8] Branch for the last state of the example with Java 8.
+
 === Building with Gradle
 Type:
 
@@ -61,4 +66,3 @@ If you have any comments or questions, please direct them to the Spock discussio
 Happy spec'ing!
 
 The Spock Framework Team
-

build.gradle

@@ -8,7 +8,7 @@ description = "Spock Framework - Example Project"
 // Spock works with Java 1.8 and above
 java {
     toolchain {
-        languageVersion.set(JavaLanguageVersion.of(8))
+        languageVersion.set(JavaLanguageVersion.of(17))
     }
 }