build.gradle

task jacocoTestReport(type: JacocoReport, dependsOn: ['testDebugUnitTest', 'createDebugCoverageReport']) {

    reports {
        xml.enabled = true
        html.enabled = true
    }

    def fileFilter = [ '**/R.class', '**/R$*.class', '**/BuildConfig.*', '**/Manifest*.*', '**/*Test*.*', 'android/**/*.*' ]
    def debugTree = fileTree(dir: "$project.buildDir/tmp/kotlin-classes/debug", excludes: fileFilter)
    def mainSrc = "$project.projectDir/src/main/kotlin"

    sourceDirectories = files([mainSrc])
    classDirectories = files([debugTree])
    executionData = fileTree(dir: project.buildDir, includes: [
            'jacoco/testDebugUnitTest.exec', 'outputs/code-coverage/connected/*coverage.ec'
    ])
}

Please refer to the full guide written by @rafaeltoledo at https://proandroiddev.com/unified-code-coverage-for-android-revisited-44789c9b722f