Builds a client with the supplied options. See [HttpClient.Builder](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.Builder.html) for a more detailed description of the options.

The `opts` map takes the following keys:

- `:connect-timeout` - connection timeout in milliseconds or a `java.time.Duration`
- `:cookie-handler` - a [java.net.CookieHandler](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/CookieHandler.html)
- `:executor` - a [java.util.concurrent.Executor](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/concurrent/Executor.html)
- `:follow-redirects` - one of `:always`, `:never` and `:normal`. Maps to the corresponding [HttpClient.Redirect](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.Redirect.html) enum.
- `:priority` - the [priority](https://developers.google.com/web/fundamentals/performance/http2/#stream_prioritization) of the request (only used for HTTP/2 requests)
- `:proxy` - a [java.net.ProxySelector](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/ProxySelector.html)
- `:ssl-context` - a [javax.net.ssl.SSLContext](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/javax/net/ssl/SSLContext.html)
- `:ssl-parameters` - a [javax.net.ssl.SSLParameters](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/javax/net/ssl/SSLParameters.html)
- `:version` - the HTTP protocol version, one of `:http1.1` or `:http2`

Equivalent to `(.build (client-builder opts))`.

Builds a [java.net.http.HttpRequest](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpRequest.html) from a map.

See [[send]] for a description of `req-map`.

Equivalent to `(.build (request-builder req-map))`.

Same as [[build-client]], but returns a [HttpClient.Builder](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.Builder.html) instead of a [HttpClient](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html).

See [[build-client]] for a description of `opts`.

Used for requests unless a client is explicitly passed. Equal to [HttpClient.newHttpClient()](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html#newHttpClient%28%29).

Sends a DELETE request to `uri`.

See [[send]] for a description of `req-map` and `opts`.

Sends a GET request to `uri`.

See [[send]] for a description of `req-map` and `opts`.

Sends a HEAD request to `uri`.

See [[send]] for a description of `req-map` and `opts`.

Sends a POST request to `uri`.

See [[send]] for a description of `req-map` and `opts`.

Sends a PUT request to `uri`.

See [[send]] for a description of `req-map` and `opts`.

Same as [[build-request]], but returns a [HttpRequest.Builder](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpRequest.Builder.html) instead of a [HttpRequest](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpRequest.html).

Converts a [HttpResponse](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpResponse.html) into a map.

The response map contains the following keys:

 - `:body` - the response body
 - `:headers` - the HTTP headers, a map where keys are strings and values are strings or a list of strings
 - `:status` - the HTTP status code
 - `:version` - the HTTP protocol version, one of `:http1.1` or `:http2`

Sends a HTTP request and blocks until a response is returned or the request
takes longer than the specified `timeout`. If the request times out, a [HttpTimeoutException](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpTimeoutException.html)
is thrown.

The `req` parameter can be a either string URL, a request map, or a [java.net.http.HttpRequest](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpRequest.html).

The request map takes the following keys:

- `:body` - the request body. Can be a string, a primitive Java byte array or a java.io.InputStream.
- `:expect-continue?` - See the [javadoc](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpRequest.Builder.html#expectContinue%28boolean%29)
- `:headers` - the HTTP headers, a map where keys are strings and values are strings or a list of strings
- `:method` - the HTTP method as a keyword (e.g `:get`, `:put`, `:post`)
- `:timeout` - the request timeout in milliseconds or a `java.time.Duration`
- `:uri` - the request uri
- `:version` - the HTTP protocol version, one of `:http1.1` or `:http2`

`opts` is a map containing one of the following keywords:

- `:as` - converts the response body to one of the following formats:
    - `:string` - a java.lang.String (default)
    - `:byte-array` - a Java primitive byte array.
    - `:input-stream` - a java.io.InputStream.

- `:client` - the [HttpClient](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html) to use for the request. If not provided the [[default-client]] will be used.

- `:raw?` - if true, skip the Ring format conversion and return the [HttpResponse](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpResponse.html

Sends a request asynchronously and immediately returns a [CompletableFuture](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html). Converts the
 eventual response to a map as per [[response->map]].

See [[send]] for a description of `req` and `opts`.

`callback` is a one argument function that will be applied to the response on completion.

`ex-handler` is a one argument function that will be called if an exception is thrown anywhere during the request.