response1.close()

    // Force a fresh connection for the next request.
    client.connectionPool.evictAll()

    // Confirm that a second request also succeeds. This should detect caching problems.
    server.enqueue(
      MockResponse
        .Builder()
        .body("def")
        .onResponseEnd(ShutdownConnection)
        .build(),
    )
    val call2 =
      client.newCall(

   * Number value = first.or(0.5); // error
   * }
   *
   * <p>As a workaround, it is always safe to cast an {@code Optional<? extends T>} to {@code
   * Optional<T>}. Casting either of the above example {@code Optional} instances to {@code
   * Optional<Number>} (where {@code Number} is the desired output type) solves the problem:
   *
   * {@snippet :

   * Collections#emptyList}, and is preferable mainly for consistency and maintainability of your
   * code.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting to any type is safe because the list will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <E> ImmutableList<E> of() {
    return (ImmutableList<E>) EMPTY;
  }

  /**

        }
      }

      static class Gist {
        Map<String, GistFile> files;
      }

      static class GistFile {
        String content;
      }
    ```

### Response Caching ([.kt][CacheResponseKotlin], [.java][CacheResponseJava])

     *          since casting to double is nondecreasing.
     *          Note that the right-hand inequality is no longer strict.
     * Math.sqrt(k * k) <= Math.sqrt(x) <= Math.sqrt((k + 1) * (k + 1))
     *          since Math.sqrt is monotonic.
     * (long) Math.sqrt(k * k) <= (long) Math.sqrt(x) <= (long) Math.sqrt((k + 1) * (k + 1))
     *          since casting to long is monotonic

			return
		}

		// Indicate we are ready to write.
		doneCh <- err

		// Wait for channel to be closed so we don't race on writes.
		<-doneCh

		// Clear so we can be called multiple times without crashing.
		doneCh = nil
	}, &closeNotifier{rc: r.Body, done: bodyDoneCh}
}

// keepHTTPResponseAlive can be used to avoid timeouts with long storage
// operations, such as bitrot verification or data usage scanning.

    }
    return Collections.unmodifiableList(causes);
  }

  /**
   * Returns {@code throwable}'s cause, cast to {@code expectedCauseType}.
   *
   * <p>Prefer this method instead of manually casting an exception's cause. For example, {@code
   * (IOException) e.getCause()} throws a {@link ClassCastException} that discards the original
   * exception {@code e} if the cause is not an {@link IOException}, but {@code

                // Clean release
                releaseHandle(handle);
                break;
        }
    }
}
```

## 10. Performance Considerations

### 10.1 Handle Caching Strategy
```java
public class HandleCache {
    private final int maxHandles = 1000;
    private final LinkedHashMap<String, HandleInfo> lruCache;
    
    public HandleCache() {

## Provider-specific Notes

* AWS
  * Support for ap-northeast-2 region (Seoul)
  * Allow cross-region image pulling with ECR
  * More reliable kube-up/kube-down
  * Enable ICMP Type 3 Code 4 for ELBs
  * ARP caching fix
  * Use /dev/xvdXX names
  * ELB:
    * ELB proxy protocol support 
	* mixed plaintext/encrypted ports support in ELBs
    * SSL support for ELB listeners
  * Allow VPC CIDR to be specified (experimental)

        .build()
  }

  @AfterEach
  fun tearDown() {
    ResponseCache.setDefault(null)
    cache.delete()
  }

  /**
   * Test that response caching is consistent with the RI and the spec.
   * http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.4
   */
  @Test
  fun responseCachingByResponseCode() {