YAML indentations

[bajiat]

Ensure that yaml output is indented properly and the file produced by OpenAPi designer can be used/viewed in Swagger Hub.

Also, ensure that the yaml indentations are properly formatted and displayed in the "Editable output" view.

[tulir]

Could you elaborate this a bit?

I'm pretty sure we can trust the YAML library, and validating it with yet another library is just pointless. If you mean that some fields are on the wrong YAML level, then it's a problem with the editor/object structure and not YAML.

Input YAML validation also seems useless: the parser error message should be enough.