code: private static InetSocketAddress overrideProxy(String proxyHostPort) {
      if (proxyHostPort == null) {
        return null;
      }
  
      String[] parts = proxyHostPort.split(":", 2);
      int port = 80;
      if (parts.length > 1) {
        port = Integer.parseInt(parts[1]);
      }
      log.warning(
          "Detected GRPC_PROXY_EXP and will honor it, but this feature will "
              + "be removed in a future release. Use the JVM flags "
              + "\"-Dhttps.proxyHost=HOST -Dhttps.proxyPort=PORT\" to set the https proxy for "
              + "this JVM.");
      return new InetSocketAddress(parts[0], port);
    }
docs: GRPC_PROXY_EXP is deprecated but let's maintain compatibility for now.