Checks validity based on the given ETag and/or date.
This function assumes the resource being checked exists.
If not, the matchesMetadata function should be used.
Optional eTag: stringCondition based on ETag.
Optional lastModified: DateCondition based on last modified date.
Optional matchesETagValid if matching any of the given ETags.
Checks validity based on the given metadata.
Optional metadata: RepresentationMetadataMetadata of the representation. Undefined if the resource does not exist.
Optional modifiedValid if modified since the given date.
Optional notValid if not matching any of the given ETags.
Optional unmodifiedValid if not modified since the given date.
The conditions of an HTTP conditional request.