code: private static void checkPreconditions(final String[] trueValues, final String[] falseValues) {
  		
  		if( trueValues == null ) {
  			throw new NullPointerException("trueValues should not be null");
  		} else if( trueValues.length == 0 ) {
  			throw new IllegalArgumentException("trueValues should not be empty");
  		}
  		
  		if( falseValues == null ) {
  			throw new NullPointerException("falseValues should not be null");
  		} else if( falseValues.length == 0 ) {
  			throw new IllegalArgumentException("falseValues should not be empty");
  		}
  		
  	}
docs: Checks the preconditions for constructing a new ParseBool processor.
  
  @param trueValues
  the array of Strings which represent true
  @param falseValues
  the array of Strings which represent false
  @throws IllegalArgumentException
  if trueValues or falseValues is empty
  @throws NullPointerException
  if trueValues or falseValues is null