docs: @Override
      public ProxyHandler createProxyHandler() {
          final HttpProxyHandler handler;
  
          // For reasons that are not immediately clear, HttpProxyHandler doesn't allow null usernames/passwords if
          // specified. If we want them to be null, we have to use the constructor that doesn't take a username/password
          // at all.
          if (this.username != null && this.password != null) {
              handler = new HttpProxyHandler(this.proxyAddress, this.username, this.password);
          } else {
              handler = new HttpProxyHandler(this.proxyAddress);
          }
  
          return handler;
      }