[builder][held_certificate_builder] to create a self-signed certificate that a test server can use
for HTTPS:

```java
HeldCertificate localhostCertificate = new HeldCertificate.Builder()
    .addSubjectAlternativeName("localhost")
    .build();
```

[`HandshakeCertificates`][handshake_certificates] keeps the certificates for a TLS handshake.

    // Generate a self-signed cert for the server to serve and the client to trust.
    val heldCertificate =
      HeldCertificate.Builder()
        .commonName("localhost")
        .addSubjectAlternativeName("localhost")
        .addSubjectAlternativeName("localhost.localdomain")
        .build()
    return@lazy HandshakeCertificates.Builder()
      .heldCertificate(heldCertificate)
      .addTrustedCertificate(heldCertificate.certificate)

    assertThat(response.handshake!!.peerPrincipal).isNull()
  }

  @Test fun `bad certificates host in insecureHosts fails with SSLException`() {
    val heldCertificate =
      HeldCertificate.Builder()
        .addSubjectAlternativeName("example.com")
        .build()
    val serverCertificates =
      HandshakeCertificates.Builder()
        .heldCertificate(heldCertificate)
        .build()

}

public final class okhttp3/tls/HeldCertificate$Builder {
	public static final field Companion Lokhttp3/tls/HeldCertificate$Builder$Companion;
	public fun <init> ()V
	public final fun addSubjectAlternativeName (Ljava/lang/String;)Lokhttp3/tls/HeldCertificate$Builder;
	public final fun build ()Lokhttp3/tls/HeldCertificate;
	public final fun certificateAuthority (I)Lokhttp3/tls/HeldCertificate$Builder;

 */
public class HttpsServer {
  public void run() throws Exception {
    HeldCertificate localhostCertificate = new HeldCertificate.Builder()
        .addSubjectAlternativeName("localhost")
        .build();

    HandshakeCertificates serverCertificates = new HandshakeCertificates.Builder()
        .heldCertificate(localhostCertificate)
        .build();

   * Host header).
   */
  @Test
  fun domainFronting() {
    val heldCertificate =
      HeldCertificate.Builder()
        .commonName("server name")
        .addSubjectAlternativeName("url-host.com")
        .build()
    val handshakeCertificates =
      HandshakeCertificates.Builder()
        .heldCertificate(heldCertificate)
        .addTrustedCertificate(heldCertificate.certificate)

    // can't use TlsUtil.localhost with a non OpenJSSE trust manager
    val heldCertificate =
      HeldCertificate.Builder()
        .commonName("localhost")
        .addSubjectAlternativeName("localhost")
        .build()
    val handshakeCertificates =
      HandshakeCertificates.Builder()
        .heldCertificate(heldCertificate)
        .addTrustedCertificate(heldCertificate.certificate)

  private val localhost: HandshakeCertificates by lazy {
    // Generate a self-signed cert for the server to serve and the client to trust.
    val heldCertificate =
      HeldCertificate.Builder()
        .addSubjectAlternativeName("localhost")
        .build()
    return@lazy HandshakeCertificates.Builder()
      .addPlatformTrustedCertificates()
      .heldCertificate(heldCertificate)
      .addTrustedCertificate(heldCertificate.certificate)

    run {
      // Generate a self-signed cert for the server to serve and the client to trust.
      val heldCertificate =
        HeldCertificate.Builder()
          .commonName(hostname)
          .addSubjectAlternativeName(hostname)
          .build()
      HandshakeCertificates.Builder()
        .heldCertificate(heldCertificate)
        .addTrustedCertificate(heldCertificate.certificate)
        .build()
    }