docs: protected void generate(XExpression expression, LightweightTypeReference needReturn, ExtraLanguageAppendable appendable,
  			IExtraLanguageGeneratorContext context) {
  		final IExpressionGenerator generator = getExpressionGenerator();
  		if (generator == null) {
  			throw new UnsupportedOperationException();
  		}
  		generator.generate(expression, needReturn, appendable, context);
  	}