Method PUT: ignore specification of protected properties which can not be set. Filtering them out of the payload list. This lets the result of a get using: class/id?@protected=true&@verbose=0 be used as input to a PUT operation without having to strip the protected properties. Note this does not raise an error if the PUT protected property is different from the value in the db. If the property is different but the etag/if-match passes, the user attempted to set the protected property and this should result in an error, but will not with this patch. Method DELETE class/id/attribute: raise error when trying to delete protected or required attribute/property. Raise UsageError when attribute doesn't exist. Method PATCH class/id: raise error when trying to replace/remove protected attribute/property raise error when trying to remove required attribute/property Catch KeyError at top level and turn into 400 error. If payload has an attribute/property that does not exist, raise UsageError which becomes a 400 error.

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