Exclude packages for jacoco report not working

Hi, I am new to gradle and have to use jacoco plugin for my students-project. I use an external json-library, which I don’t want to be included in my code coverage nor the report.

Thus I tried to adjust my gradle script with a solution I found on stackoverflow.com , but it doesn’t work. Anybody have an idea, why this doesn’t work?

jacocoTestReport {
    dependsOn test // always run tests before generating new report
    finalizedBy jacocoTestCoverageVerification // always check coverage after generating report

    afterEvaluate {
        classDirectories.setFrom(files(classDirectories.files.collect {
            fileTree(dir: it, exclude: 'org/json/**')
        }))
    }
}

// TODO: (for students) Add limits or adjust limit to your team's Definition of Done
jacocoTestCoverageVerification {
    violationRules {
        rule {
            limit {
                counter = "BRANCH"
                value = "COVEREDRATIO"
                minimum = 0.03
            }
        }
    }

    afterEvaluate {
        classDirectories.setFrom(files(classDirectories.files.collect {
            fileTree(dir: it, exclude: 'org/json/**')
        }))
    }
}

I use gradle version 7.0.2