code: static int toPosixFileMode(ZTFilePermissions permissions) {
      int mode = 0;
      
      mode |= addFlag(permissions.isOwnerCanExecute(),  OWNER_EXECUTE_FLAG);
      mode |= addFlag(permissions.isGroupCanExecute(),  GROUP_EXECUTE_FLAG);
      mode |= addFlag(permissions.isOthersCanExecute(), OTHERS_EXECUTE_FLAG);
      
      mode |= addFlag(permissions.isOwnerCanWrite(),  OWNER_WRITE_FLAG);
      mode |= addFlag(permissions.isGroupCanWrite(),  GROUP_WRITE_FLAG);
      mode |= addFlag(permissions.isOthersCanWrite(), OTHERS_WRITE_FLAG);
      
      mode |= addFlag(permissions.isOwnerCanRead(),  OWNER_READ_FLAG);
      mode |= addFlag(permissions.isGroupCanRead(),  GROUP_READ_FLAG);
      mode |= addFlag(permissions.isOthersCanRead(), OTHERS_READ_FLAG);
      
      return mode;
    }
docs: Convert {@link ZTFilePermissions} to POSIX file permission bit array.
  
  
  @param permissions permissions
  @return Posix mode