code: @NullSafe
    public static boolean isDigits(String value) {
  
      for (char chr : toCharArray(value)) {
        if (!Character.isDigit(chr)) {
          return false;
        }
      }
  
      return hasText(value);
    }
docs: Determines whether the String value represents a number, i.e. consists entirely of digits.
  
  @param value the String value for determination as a number.
  @return a boolean value indicating if the String value represents a number.
  @see java.lang.Character#isDigit(char)
  @see #hasText(String)
  @see #toCharArray(String)