code: private static void checkPreconditions(final List<String> forbiddenSubStrings) {
  		if( forbiddenSubStrings == null ) {
  			throw new NullPointerException("forbiddenSubStrings list should not be null");
  		} else if( forbiddenSubStrings.isEmpty() ) {
  			throw new IllegalArgumentException("forbiddenSubStrings list should not be empty");
  		}
  	}
docs: Checks the preconditions for creating a new ForbidSubStr processor with a List of forbidden substrings.
  
  @param forbiddenSubStrings
  the forbidden substrings
  @throws NullPointerException
  if forbiddenSubStrings is null
  @throws IllegalArgumentException
  if forbiddenSubStrings is empty