code: public Proxy setSocksVersion(Integer socksVersion) {
      verifyProxyTypeCompatibility(ProxyType.MANUAL);
      this.proxyType = ProxyType.MANUAL;
      this.socksVersion = socksVersion;
      return this;
    }
docs: Specifies which version of SOCKS to use (4 or 5).
  
  @param socksVersion SOCKS version, 4 or 5
  @return reference to self