I assume that

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

is the same as

tasks.compileKotlin.configure {
	kotlinOptions.jvmTarget = "1.8"
}

Can somebody explain to me how this magic works?

compileKotlin

is a property of type

TaskProvider<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>

which is an interface with two abstract methods, so it can't be SAM, right?

there is a #gradle channel