[android] Cannot inline bytecode built with JVM target 1.8 into bytecode that is being built with JVM target 1.6

in most cases this is enough:

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
    kotlinOptions.jvmTarget = "1.8"
}

if you have declared custom Gradle tasks like integrationTest for example, add a configuration for compile<YourTaskName>Kotlin as well:

compileIntegrationTestKotlin {
    kotlinOptions.jvmTarget = "1.8"
}