code: def _set_blob_metadata(self, sd, metadata):
          # type: (SyncCopy, blobxfer.models.synccopy.Descriptor, dict) -> None
          
          blobxfer.operations.azure.blob.set_blob_metadata(
              sd.dst_entity, metadata)
          if blobxfer.util.is_not_empty(sd.dst_entity.replica_targets):
              for ase in sd.dst_entity.replica_targets:
                  blobxfer.operations.azure.blob.set_blob_metadata(ase, metadata)
docs: Set blob metadata
          :param SyncCopy self: this
          :param blobxfer.models.synccopy.Descriptor sd: synccopy descriptor
          :param dict metadata: metadata dict
          :param dict metadata: metadata dict