code: public static String getProxy() throws InvalidProxyException {
          String proxy = getProgramProperty(PROXY);
          if (proxy == null) {
              throw new InvalidProxyException(PROXY_ISNT_SET);
          }
          String[] proxyParts = proxy.split(":");
          if (proxyParts.length != 2) {
              throw new InvalidProxyException("Proxy '" + proxy + "' isn't valid. Must contain address and port, without protocol");
          }
          try {
              Integer.parseInt(proxyParts[1]);
          } catch (NumberFormatException e) {
              throw new InvalidProxyException("Proxy '" + proxy + "' isn't valid. Must contain address and port, without protocol. Invalid port provided. " + e);
          }
          return proxy;
      }
docs: Retrieves the proxy property if it is set. This could be to something local, or in the cloud.
  Provide the protocol, address, and port
  
  @return String: the set proxy address, null if none are set