build: enforce Groovy version override

Setting `groovy.version` property does not seem to suffice to override the groovy version in the bom.

build.gradle

@@ -10,12 +10,12 @@ ext.set('grailsVersion', libs.versions.grails.get())
 ext.set('isSnapshot', projectVersion.endsWith('-SNAPSHOT'))
 ext.set('isReleaseVersion', !isSnapshot)
 
-def groovyVersion = findProperty('groovyVersion') ?: System.getenv('GROOVY_VERSION')
-if (groovyVersion) {
-    ext.set('groovy.version', groovyVersion)
+String customGroovyVersion = findProperty('groovyVersion') ?: System.getenv('GROOVY_VERSION')
+if (customGroovyVersion) {
+    logger.warn("Using custom Groovy version: $customGroovyVersion")
 }
 
-if(isReleaseVersion) {
+if (isReleaseVersion) {
     nexusPublishing {
         String nexusUser = System.getenv('SONATYPE_USERNAME')
         String nexusPass = System.getenv('SONATYPE_PASSWORD')
@@ -36,13 +36,24 @@ subprojects {
     apply plugin: 'groovy'
 
     version = rootProject.version
+
+    if (customGroovyVersion) {
+        configurations.configureEach {
+            resolutionStrategy.eachDependency { DependencyResolveDetails details ->
+                if (details.requested.group == 'org.apache.groovy') {
+                    details.useVersion(customGroovyVersion)
+                }
+            }
+        }
+    }
+
     repositories {
         mavenCentral()
         maven { url = 'https://repo.grails.org/grails/core' }
         // mavenLocal() // Keep, this will be uncommented and used by CI (groovy-joint-workflow)
-        if (groovyVersion?.endsWith('-SNAPSHOT')) {
+        if (customGroovyVersion?.endsWith('-SNAPSHOT')) {
             // Used for testing locally against the latest snapshot of Groovy
-            // Usage: ./gradlew -PgroovyVersion=X.X.X-SNAPSHOT build
+            // Usage: ./gradlew build -P"groovyVersion=X.X.X-SNAPSHOT"
             maven {
                 name = 'ASF Snapshot repo'
                 url = 'https://repository.apache.org/content/repositories/snapshots'