* this client silently recovers from the following problems:
     *
     * * **Unreachable IP addresses.** If the URL's host has multiple IP addresses,
     *   failure to reach any individual IP address doesn't fail the overall request. This can
     *   increase availability of multi-homed services.
     *
     * * **Stale pooled connections.** The [ConnectionPool] reuses sockets

 * The query is optional: it can be null, empty, or non-empty. For many HTTP URLs the query string
 * is subdivided into a collection of name-value parameters. This class offers methods to set the
 * query as the single string, or as individual name-value parameters. With name-value parameters
 * the values are optional and names may be repeated.
 *
 * ### Fragment
 *

    one timeout period.

    Use `OkHttpClient.Builder.callTimeout()` to specify the default duration and `Call.timeout()` to
    specify the timeout of an individual call.

 *  New: Return values and fields are now non-null unless otherwise annotated.
 *  New: `LoggingEventListener` makes it easy to get basic visibility into a call's performance.