docs: public static boolean isWallet(InputStream is) {
          try {
              final CodedInputStream cis = CodedInputStream.newInstance(is);
              final int tag = cis.readTag();
              final int field = WireFormat.getTagFieldNumber(tag);
              if (field != 1) // network_identifier
                  return false;
              final String network = cis.readString();
              return NetworkParameters.fromID(network) != null;
          } catch (IOException x) {
              return false;
          }
      }