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Another way to associate a Content-MD5 value with an object is to have Swarm compute the ContentMD5 for the body data of the request. To do this, include Include the gencontentmd5 query argument in the request to perform this. Swarm returns the Content-MD5 as a header in the 201 Created response. Once computed, the Content-MD5 data is stored with the object and returned as a response header for any subsequent GET or HEAD requests. Note that the gencontentmd5 query argument replaces use of the "Expect: Content-MD5" request header, which is deprecated per RFC 2731. (v9.2)
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