code: @NullSafe
    public static boolean isLetters(String value) {
  
      for (char chr : toCharArray(value)) {
        if (!Character.isLetter(chr)) {
          return false;
        }
      }
  
      return hasText(value);
    }
docs: Determines whether the String value consists entirely of letters.
  
  @param value the String value for determination as text.
  @return a boolean value indicating if the String value consists entirely of letters.
  @see java.lang.Character#isLetter(char)
  @see #hasText(String)
  @see #toCharArray(String)