Don't use HTTP/2 with client certificates

import at.bitfire.davdroid.model.Credentials

import at.bitfire.davdroid.settings.AccountSettings

import at.bitfire.davdroid.settings.Settings

import okhttp3.Cache

import okhttp3.Interceptor

import okhttp3.OkHttpClient

import okhttp3.Response

import okhttp3.*

import okhttp3.internal.tls.OkHostnameVerifier

import okhttp3.logging.HttpLoggingInterceptor

import java.io.File

                                key.takeIf { forAlias == alias }

                    }

                }

                // HTTP/2 doesn't support client certificates (yet)

                // see https://tools.ietf.org/html/draft-ietf-httpbis-http2-secondary-certs-04

                orig.protocols(listOf(Protocol.HTTP_1_1))

            } catch (e: Exception) {

                logger.log(Level.SEVERE, "Couldn't set up provider certificate authentication", e)

            }