code: @NullSafe
    public static String toUpperCase(String value) {
      return value != null ? value.toUpperCase() : null;
    }
docs: Converts the String value to all UPPER case characters.  toUpperCase is a null-safe operation.
  
  @param value the String value who's characters are all converted to UPPER case.
  @return the String value with all UPPER case characters.
  @see #toLowerCase(String)
  @see java.lang.String#toUpperCase()