Additional validation of JSON/EST

[victornicolet]

Describe the improvement you'd like to request

Some policies parse in JSON format, but converting them to the Cedar format results in policies that fail to parse. Additional validation should be done when parsing JSON, or at least when converting JSON policies to Cedar policy.

There are two examples of this for Policies:

1. JSON policy with zero-argument method style call doesn't parse when converted to Cedar syntax #2116 , the JSON policy parsing is more lenient with respect to zero-argument method style
2. extend the 'has' relation in EST and JSON policy format #2154 introduces the extended has operator in the JSON format. However, in Cedar format, the attributes in the extended form must be identifiers. This is not validated in the JSON format, and therefore can result in Cedar like e has attr."not identifier".attr2. This problem is currently mitigated by the fact that the conversion desugars, and therefore this is not an issue in the CLI's conversion tools.

Describe alternatives you've considered

No response

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this internal improvement
• ⚠️ This feature might incur a breaking change