code: public static boolean toBoolean(@Nullable final String booleanStr) {
          if (!isValid(booleanStr)) {
              throw new IllegalArgumentException(booleanStr + ExceptionValues.EXCEPTION_DELIMITER + ExceptionValues.INVALID_BOOLEAN_VALUE);
          }
          return BooleanUtils.toBoolean(getLowerCaseString(booleanStr));
      }
docs: If the booleanStr is a valid boolean (see isValid) it returns the boolean value, otherwise it throws an exception
  
  @param booleanStr the string to convert to boolean
  @return true if the booleanStr is 'true', false if it's 'false'
  @throws IllegalArgumentException if the booleanStr is not a valid boolean