I just read in the 8.1.1 release notes that this was added in SMB 2.1 support. https://library.netapp.com/ecm/ecm_get_file/ECMP1140403 (release notes)
Data ONTAP File Access and Protocols Management Guide for 7-Mode. https://library.netapp.com/ecm/ecm_get_file/ECMP1120826 (user guide with more detail)
Retrieval of content hashes used by BranchCache
BranchCache-enabled storage systems use content hashes to provide clients with information
about cached content.
• cifs branchcache hash stat
• cifs branchcache set key