Hello!

According to https://datatracker.ietf.org/doc/html/rfc7946#section-3.2, the Id field of the Feature, if present, can be either number or string:

If a Feature has a commonly used identifier, that identifier
SHOULD be included as a member of the Feature object with the name
"id", and the value of this member is either a JSON string or
number.

However, current implementation only supports deserialization of string values for this field.
Proposed solutions:

• A custom JSON converter for this field, with storing the value as a string.
• Storing the value as a discriminated union of string and int (or long).

Best regards,
Dmitry