Fix Jacoco aggregate report configuration for Gradle 9 (spiffe#387)

* Fix jacocoTestReport configuration for Gradle 9

Configure jacocoClasspath and report output locations explicitly and apply the
jacoco plugin at the root project to satisfy Gradle 9 task validation.

Signed-off-by: Max Lambrecht <maxlambrecht@gmail.com>

* Fix error

Signed-off-by: Max Lambrecht <maxlambrecht@gmail.com>

---------

Signed-off-by: Max Lambrecht <maxlambrecht@gmail.com>

Author: maxlambrecht

build.gradle

@@ -1,4 +1,5 @@
 plugins {
+    id 'jacoco'
     id 'com.google.osdetector' version '1.7.3'
     id 'jvm-test-suite'
     id 'com.vanniktech.maven.publish' version '0.35.0' apply false
@@ -116,40 +117,43 @@ subprojects {
             )
         }
     }
+
+    // Disable per-module JaCoCo reports; generate a single aggregate report at root
+    tasks.withType(JacocoReport).configureEach {
+        enabled = false
+    }
 }
 
 tasks.register('jacocoTestReport', JacocoReport) {
-    // Gather execution data from all subprojects
-    executionData.from(
-            fileTree(rootDir) {
-                include '**/build/jacoco/*.exec'
-            }
-    )
+    dependsOn(subprojects.collect { it.tasks.named('test') })
+
+    jacocoClasspath = configurations.jacocoAnt
 
-    // Add all relevant sourcesets from the subprojects
-    subprojects.each { p ->
-        sourceSets p.sourceSets.main
+    executionData = fileTree(rootDir) {
+        include '**/build/jacoco/*.exec'
+        include '**/build/jacoco/*.ec'
     }
 
-    // Filter out autogenerated or internal code
-    classDirectories.setFrom(
-            files(classDirectories.files.collect { dir ->
-                fileTree(dir: dir, exclude: [
-                        '**/grpc/**',
-                        '**/exception/**',
-                        '**/internal/**'
-                ])
-            })
-    )
+    def mainSourceDirs = files(subprojects.collect { p -> p.sourceSets.main.allSource.srcDirs })
+    def mainClassDirs  = files(subprojects.collect { p -> p.sourceSets.main.output })
+
+    sourceDirectories = mainSourceDirs
+
+    classDirectories = files(mainClassDirs.files.collect { dir ->
+        fileTree(dir: dir, exclude: [
+                '**/grpc/**',
+                '**/exception/**',
+                '**/internal/**'
+        ])
+    })
 
     reports {
         xml.required = true
         html.required = true
-    }
-}
 
-tasks.named('jacocoTestReport') {
-    dependsOn(subprojects.collect { it.tasks.named('test') })
+        xml.outputLocation = layout.buildDirectory.file('reports/jacoco/jacoco.xml')
+        html.outputLocation = layout.buildDirectory.dir('reports/jacoco/html')
+    }
 }
 
 // copy submodules jars to a common folder for deploy