String code = requestUrl.queryParameter("code");
    String stateString = requestUrl.queryParameter("state");
    ByteString state = stateString != null ? ByteString.decodeBase64(stateString) : null;

    Listener listener;
    synchronized (this) {
      listener = listeners.get(state);
    }

    if (code == null || listener == null) {
      return new MockResponse()

import assertk.assertions.isEmpty
import assertk.assertions.isEqualTo
import okhttp3.CertificatePinner.Companion.sha1Hash
import okhttp3.CertificatePinner.Pin
import okhttp3.tls.HeldCertificate
import okio.ByteString.Companion.decodeBase64
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Assertions.assertFalse
import org.junit.jupiter.api.Assertions.assertTrue
import org.junit.jupiter.api.Test