code: public Proxy setHttpProxy(String httpProxy) {
      verifyProxyTypeCompatibility(ProxyType.MANUAL);
      this.proxyType = ProxyType.MANUAL;
      this.httpProxy = httpProxy;
      return this;
    }
docs: Specify which proxy to use for HTTP connections.
  
  @param httpProxy the proxy host, expected format is <code>hostname:1234</code>
  @return reference to self