project(':projectA') {
    dependencies {
        compileOnly 'org.gradle.test:compileOnly:1.0'
    }
}

project(':projectB') {
    dependencies {
        api project(':projectA')
    }

    task checkClasspath {
        def compileClasspathFiles = configurations.compileClasspath.files
        def projectAJavaDestDir = project(':projectA').compileJava.destinationDirectory
        doLast {

                }
            }
        """

        file('a/build.gradle') << '''
            dependencies {
                implementation project(':b')
            }

            task checkClasspath {
                def classpath = compileJava.classpath
                doLast {
                    def compileClasspath = classpath.files*.name
                    assert !compileClasspath.contains('b.jar')