return when (protocol) {
        HTTP_1_0.protocol -> HTTP_1_0
        HTTP_1_1.protocol -> HTTP_1_1
        H2_PRIOR_KNOWLEDGE.protocol -> H2_PRIOR_KNOWLEDGE
        HTTP_2.protocol -> HTTP_2
        SPDY_3.protocol -> SPDY_3
        QUIC.protocol -> QUIC
        else -> {
          // Support HTTP3 draft like h3-29
          if (protocol.startsWith(HTTP_3.protocol)) HTTP_3 else throw IOException("Unexpected protocol: $protocol")

class ProtocolTest {
  @Test
  fun testGetKnown() {
    assertThat(get("http/1.0")).isEqualTo(Protocol.HTTP_1_0)
    assertThat(get("http/1.1")).isEqualTo(Protocol.HTTP_1_1)
    assertThat(get("spdy/3.1")).isEqualTo(Protocol.SPDY_3)
    assertThat(get("h2")).isEqualTo(Protocol.HTTP_2)
    assertThat(get("h2_prior_knowledge")).isEqualTo(Protocol.H2_PRIOR_KNOWLEDGE)
    assertThat(get("quic")).isEqualTo(Protocol.QUIC)

    }
  }

  @Test fun spdy3IsRemovedFromProtocols() {
    val protocols =
      mutableListOf(
        Protocol.HTTP_1_1,
        Protocol.SPDY_3,
      )
    val client =
      OkHttpClient.Builder()
        .protocols(protocols)
        .build()
    assertThat(client.protocols).containsExactly(Protocol.HTTP_1_1)
  }

          "protocols must not contain null"
        }

        // Remove protocols that we no longer support.
        @Suppress("DEPRECATION")
        protocolsCopy.remove(Protocol.SPDY_3)

        if (protocolsCopy != this.protocols) {
          this.routeDatabase = null
        }

        // Assign as an unmodifiable list. This is effectively immutable.

	public static final field HTTP_2 Lokhttp3/Protocol;
	public static final field HTTP_3 Lokhttp3/Protocol;
	public static final field QUIC Lokhttp3/Protocol;
	public static final field SPDY_3 Lokhttp3/Protocol;
	public static final fun get (Ljava/lang/String;)Lokhttp3/Protocol;
	public static fun getEntries ()Lkotlin/enums/EnumEntries;
	public fun toString ()Ljava/lang/String;