apply {
        // Create a private copy of the list.
        val protocolsCopy = protocols.toMutableList()

        // Validate that the list has everything we require and nothing we forbid.
        require(Protocol.H2_PRIOR_KNOWLEDGE in protocolsCopy || HTTP_1_1 in protocolsCopy) {
          "protocols must contain h2_prior_knowledge or http/1.1: $protocolsCopy"
        }

    HTTP/2 server, close all but the first connection.
 *  Fix: Fail the HTTP/2 connection if first frame isn't `SETTINGS`.
 *  Fix: Forbid spaces in header names.
 *  Fix: Don't offer to do gzip if the request is partial.
 *  Fix: MockWebServer is now usable with JUnit 5. That update [broke the rules][junit_5_rules].

     *
     * @throws IllegalArgumentException If this is not a well-formed HTTP or HTTPS URL.
     */
    @JvmStatic
    @JvmName("get")
    fun String.toHttpUrl(): HttpUrl = Builder().parse(null, this).build()

    /**
     * Returns a new `HttpUrl` representing `url` if it is a well-formed HTTP or HTTPS URL, or null
     * if it isn't.
     */
    @JvmStatic
    @JvmName("parse")

   *
   * @param expression a boolean expression
   * @param errorMessageTemplate a template for the exception message should the check fail. The
   *     message is formed by replacing each {@code %s} placeholder in the template with an
   *     argument. These are matched by position - the first {@code %s} gets {@code

      return filter(unfiltered().tailSet(fromElement, inclusive), predicate);
    }
  }

  /**
   * Returns every possible list that can be formed by choosing one element from each of the given
   * sets in order; the "n-ary <a href="http://en.wikipedia.org/wiki/Cartesian_product">Cartesian
   * product</a>" of the sets. For example:
   *
   * {@snippet :

      "http://[0.0.0.0:0:0:0:0:0:1]/",
      "Invalid URL host: \"[0.0.0.0:0:0:0:0:0:1]\"",
    )
  }

  @Test
  fun hostIpv6WithIncompleteIpv4Suffix() {
    // To Chrome & Safari these are well-formed; Firefox disagrees. (We're consistent with Firefox).
    assertInvalid(
      "http://[0:0:0:0:0:1:255.255.255.]/",
      "Invalid URL host: \"[0:0:0:0:0:1:255.255.255.]\"",
    )
    assertInvalid(