This rule belongs to the
yaml-syntax-validation ruleset and states that:
The key content of the key-value pair (or mapping) must not use
null unless it is intended to be a property name in which case it must be enclosed in quotes. Similarly, use of any other YAML reserved keywords must be avoided as key names unless they be enclosed in quotes.
|Mapping key could not be parsed.
- If there is a property with key equal to
null, enclose it in quotes.