val header = request.getHeader("xyz")

header

String!

getHeader

null

this

MutableList

fun uploadedFile(fileName: String): UploadedFile? {
    val uploadedFiles = uploadedFiles(fileName)
    return if (uploadedFiles.isNotEmpty()) uploadedFiles[0] else null;
}

component1()

component2()

Map

filter

filterTo

val componentArgs: List<Pair<Int, Component>> = args
        .mapIndexed { idx, it -> idx to it }
        .filter { it.second is Component }
        .map { it.first to it.second as Component }

src/main/jakewharton