public static HttpClientBuilder create() {
        return new HttpClientBuilder();
    }
Builder for {@link CloseableHttpClient} instances.
<p>
When a particular component is not explicitly set this class will
use its default implementation. System properties will be taken
into account when configuring the default implementations when
{@link #useSystemProperties()} method is called prior to calling
{@link #build()}.
</p>
<ul>
 <li>http.proxyHost</li>
 <li>http.proxyPort</li>
 <li>https.proxyHost</li>
 <li>https.proxyPort</li>
 <li>http.nonProxyHosts</li>
 <li>https.proxyUser</li>
 <li>http.proxyUser</li>
 <li>https.proxyPassword</li>
 <li>http.proxyPassword</li>
 <li>http.keepAlive</li>
 <li>http.agent</li>
</ul>
<p>
Please note that some settings used by this class can be mutually
exclusive and may not apply when building {@link CloseableHttpClient}
instances.
</p>

@since 4.3
httpclient5/src/main/java/org/apache/hc/client5/http/impl/classic/HttpClientBuilder.java