getEntityTag

Returns the full EntityTag from the ETag response header — including a weak validator (W/"..."), unlike getETag which reports only strong tags. Returns null when the header is absent or blank.

Use this when the strength matters: a strong tag drives an If-Match conditional write, while a weak tag (all Node Solid Server emits for RDF) can't satisfy If-Match and the caller should fall back to If-Unmodified-Since instead.