code: public HttpClientBuilder keyStore(URL url, String password) {
  		if (sslHostConfig == null) {
  			throw new IllegalStateException("ssl(String) must be called before this");
  		}
  		sslHostConfig.keyStoreUrl = url;
  		sslHostConfig.keyStorePassword = password;
  		return this;
  	}
docs: Configures a key store for the current SSL host (see
  {@link #ssl(String)}). If set, SSL server validation will be used (i.e.
  the server certificate will be requested and validated).
  
  @param url		URL from which to obtain key store
  @param password	key store password
  @return this
  @see #ssl(String)
  @see #trustKeyStore(URL, String)