meta fails because to generates a tuple.

example.kt

import org.http4k.contract.ApiInfo
import org.http4k.contract.ApiKey
import org.http4k.contract.OpenApi
import org.http4k.contract.RouteMeta
import org.http4k.contract.bindContract
import org.http4k.contract.contract
import org.http4k.contract.meta
import org.http4k.core.Body
import org.http4k.core.ContentType.Companion.TEXT_PLAIN
import org.http4k.core.Filter
import org.http4k.core.HttpHandler
import org.http4k.core.Method.GET
import org.http4k.core.Request
import org.http4k.core.Response
import org.http4k.core.Status
import org.http4k.core.Status.Companion.OK
import org.http4k.core.then
import org.http4k.core.with
import org.http4k.filter.ResponseFilters
import org.http4k.format.Jackson
import org.http4k.lens.Query
import org.http4k.lens.int
import org.http4k.lens.string
import org.http4k.routing.RoutingHttpHandler
import java.time.Clock
import java.time.Duration

fun main(args: Array<String>) {
    fun provideServer(): RoutingHttpHandler {

        fun ping(): HttpHandler = {
            Response(Status.OK).with(
                Body.string(TEXT_PLAIN).toLens() of "pong"
            )
        }

        val filter: Filter = ResponseFilters.ReportRouteLatency(Clock.systemUTC(), { name: String, latency: Duration ->
            println(name + " took " + latency)
        })

        val security = ApiKey(Query.int().required("apiKey"), {
            println("foo" + (it == 42))
            it == 42
        })

        val contract = contract(OpenApi(ApiInfo("the greatest api", "v1.0"), Jackson), "/docs/swagger.json", security,
            "/ping" meta {
                summary = "ping"
                description =  "Are we still there?"
                returning("Pong" to OK)
            } bindContract GET to ping()
        )
        return filter.then(contract)
    }

    val app = provideServer()
    val response = app(Request(GET, "/ping").query("apiKey", "42"))
    println(response)
    println(app(Request(GET, "/docs/swagger.json").query("apiKey", "42")))
}