Adapt boot2-test for Gradle 9 compatiblity

Normally, the Spring Boot 2 Gradle Plugin would not be compatible with Gradle 9+
To get around this issue, we use the dependency-management plugin in isolation
as described here: https://docs.spring.io/spring-boot/docs/2.7.7/gradle-plugin/reference/htmlsingle/#managing-dependencies.dependency-management-plugin.using-in-isolation
This way, we get proper test execution and realistic version resolution on Gradle 9

Author: beatbrot

settings.gradle

@@ -114,8 +114,7 @@ if (javaVersion == 8) {
 include "spock-unitils"
 
 if (javaVersion <= 17) {
-  // include "spock-spring:boot2-test" TODO adapt this according to the outstanding discussion
-  // https://github.com/spockframework/spock/discussions/2200
+  include "spock-spring:boot2-test"
 }
 include "spock-spring:spring3-test"
 include "spock-spring:spring5-test"

spock-spring/boot2-test/boot2-test.gradle

@@ -1,3 +1,5 @@
+import org.springframework.boot.gradle.plugin.SpringBootPlugin
+
 /*
  * Copyright 2018 the original author or authors.
  *
@@ -15,8 +17,18 @@
  */
 
 plugins {
+  // Normally, the Spring Boot 2 Gradle Plugin would not be compatible with Gradle 9+
+  // To get around this issue, we use the dependency-management plugin in isolation
+  // as described here: https://docs.spring.io/spring-boot/docs/2.7.7/gradle-plugin/reference/htmlsingle/#managing-dependencies.dependency-management-plugin.using-in-isolation
+  // This way, we get proper test execution and realistic version resolution on Gradle 9
+  id 'org.springframework.boot' version "2.7.18" apply false
   id "io.spring.dependency-management" version "1.1.7"
-  id 'org.springframework.boot' version "2.7.18"
+}
+
+dependencyManagement {
+  imports {
+    mavenBom SpringBootPlugin.BOM_COORDINATES
+  }
 }
 
 // Spring dependency management downgrades the jupiter version to 5.7.2 otherwise