*  Fix: Don't use brackets formatting IPv6 host names in MockWebServer.
 *  Fix: Don't permit cache iterators to remove entries that are being written.


## Version 4.0.1

_2019-07-10_

 *  Fix: Tolerate null-hostile lists in public API. Lists created with `List.of(...)` don't like it
    when you call `contains(null)` on them!

    checkInitialCapacity(2, 4, 2);
    checkInitialCapacity(2, 5, 4);
    checkInitialCapacity(2, 6, 4);
    checkInitialCapacity(2, 7, 4);
    checkInitialCapacity(2, 8, 4);

    checkInitialCapacity(4, 0, 1);
    checkInitialCapacity(4, 1, 1);
    checkInitialCapacity(4, 2, 1);
    checkInitialCapacity(4, 3, 1);
    checkInitialCapacity(4, 4, 1);
    checkInitialCapacity(4, 5, 2);
    checkInitialCapacity(4, 6, 2);

    checkInitialCapacity(2, 4, 2);
    checkInitialCapacity(2, 5, 4);
    checkInitialCapacity(2, 6, 4);
    checkInitialCapacity(2, 7, 4);
    checkInitialCapacity(2, 8, 4);

    checkInitialCapacity(4, 0, 1);
    checkInitialCapacity(4, 1, 1);
    checkInitialCapacity(4, 2, 1);
    checkInitialCapacity(4, 3, 1);
    checkInitialCapacity(4, 4, 1);
    checkInitialCapacity(4, 5, 2);
    checkInitialCapacity(4, 6, 2);

        }
      }
    ```

### Handling authentication ([.kt][AuthenticateKotlin], [.java][AuthenticateJava])

OkHttp can automatically retry unauthenticated requests. When a response is `401 Not Authorized`, an `Authenticator` is asked to supply credentials. Implementations should build a new request that includes the missing credentials. If no credentials are available, return null to skip the retry.

    checkInitialCapacity(2, 4, 2);
    checkInitialCapacity(2, 5, 4);
    checkInitialCapacity(2, 6, 4);
    checkInitialCapacity(2, 7, 4);
    checkInitialCapacity(2, 8, 4);

    checkInitialCapacity(4, 0, 1);
    checkInitialCapacity(4, 1, 1);
    checkInitialCapacity(4, 2, 1);
    checkInitialCapacity(4, 3, 1);
    checkInitialCapacity(4, 4, 1);
    checkInitialCapacity(4, 5, 2);
    checkInitialCapacity(4, 6, 2);

    checkInitialCapacity(2, 4, 2);
    checkInitialCapacity(2, 5, 4);
    checkInitialCapacity(2, 6, 4);
    checkInitialCapacity(2, 7, 4);
    checkInitialCapacity(2, 8, 4);

    checkInitialCapacity(4, 0, 1);
    checkInitialCapacity(4, 1, 1);
    checkInitialCapacity(4, 2, 1);
    checkInitialCapacity(4, 3, 1);
    checkInitialCapacity(4, 4, 1);
    checkInitialCapacity(4, 5, 2);
    checkInitialCapacity(4, 6, 2);

    }.also { expected ->
      assertThat(expected.errorCode).isEqualTo(errorCode)
    }
  }

  @Test
  fun recoverFromConnectionNoNewStreamsOnFollowUp() {
    server.enqueue(MockResponse(code = 401))
    server.enqueue(
      MockResponse
        .Builder()
        .onRequestStart(CloseStream(ErrorCode.INTERNAL_ERROR.httpCode))
        .build(),
    )
    server.enqueue(MockResponse(body = "DEF"))

    assertCached(false, 304)
    assertCached(false, 305)
    assertCached(false, 306)
    assertCached(true, 307)
    assertCached(true, 308)
    assertCached(false, 400)
    assertCached(false, 401)
    assertCached(false, 402)
    assertCached(false, 403)
    assertCached(true, 404)
    assertCached(true, 405)
    assertCached(false, 406)
    assertCached(false, 408)
    assertCached(false, 409)

    * This includes several bug fixes in Starlette.
* ⬆️ Upgrade Uvicorn max version in public extras: all. From `>=0.12.0,<0.18.0` to `>=0.12.0,<0.19.0`. PR [#5401](https://github.com/tiangolo/fastapi/pull/5401) by [@tiangolo](https://github.com/tiangolo).

### Internal

03FF          ; mapped                 ; 037D          # 4.1  GREEK CAPITAL REVERSED DOTTED LUNATE SIGMA SYMBOL
0400          ; mapped                 ; 0450          # 3.0  CYRILLIC CAPITAL LETTER IE WITH GRAVE
0401          ; mapped                 ; 0451          # 1.1  CYRILLIC CAPITAL LETTER IO
0402          ; mapped                 ; 0452          # 1.1  CYRILLIC CAPITAL LETTER DJE