code: @Override
    public void endVisit(PrefixExpression node) {
      Boolean value = getReplaceableValue(node.getOperand());
      if (node.getOperator() == PrefixExpression.Operator.NOT && value != null) {
        node.replaceWith(new BooleanLiteral(!value, typeUtil));
      }
    }
docs: Invert ! boolean constant expressions.