Unknown fields

When the API receives JSON containing fields that are not recognized or used by the endpoint, it will — on a best-effort basis — return an X-TD-Unknown-Fields header. This header contains a comma-separated list of the unrecognized fields.

While receiving unknown fields is not considered an error, it may indicate a potential issue, such as incorrect or misspelled field names. Monitoring this header can help identify and correct such mistakes.

For example, if the header returns valid_fro,name, it suggests that the valid_fro field was misspelled (it should be valid_from), and the field name is not used by this endpoint.

Implicit fields

Some fields which are documented to be required are not actually required in practice. This is because we can not make these fields truely required without breaking users that rely on the fields being optional.

That is why we have added the X-TD-Implicit-Fields header. This header is added to the response when a field was not provided even though the field is documented to be required (much like the X-TD-Unknown-Fields header). Importantly, this allows users to detect potential issues without breaking anyones implementation.

Existing fields can be made truely required when there is enough evidence that no user relies on the field being optional.