code: public static int checkArgPositive(final int arg, final String argNameOrErrorMsg) {
          if (arg <= 0) {
              if (argNameOrErrorMsg.indexOf(' ') == N.INDEX_NOT_FOUND) {
                  throw new IllegalArgumentException("'" + argNameOrErrorMsg + "' can not be zero or negative: " + arg);
              } else {
                  throw new IllegalArgumentException(argNameOrErrorMsg);
              }
          }
  
          return arg;
      }
docs: Checks if the specified {@code arg} is positive, and throws {@code IllegalArgumentException} if it is not.
  
  @param arg
  @param argNameOrErrorMsg
  @throws IllegalArgumentException if the specified {@code arg} is negative.