Before compileOptions { sourceCompatibility = JavaVersion.VERSION_1_8 targetCompatibility = JavaVersion.VERSION_1_8 } kotlinOptions { jvmTarget = "1.8" freeCompilerArgs = listOf("-Xjvm-default=enable") } After >>> JavaVersion.VERSION_1_8.toString() compileOptions { sourceCompatibility = JavaVersion.VERSION_1_8 targetCompatibility = JavaVersion.VERSION_1_8 } kotlinOptions { jvmTarget = JavaVersio..