str
Required. The stream that is the target of the append
operation. This value must be specified for the initial
request. If subsequent requests specify the stream name, it
must equal to the value provided in the first request. To
write to the \_default stream, populate this field with a
string in the format
projects/{project}/datasets/{dataset}/tables/{table}/_default.
offset
google.protobuf.wrappers_pb2.Int64Value
If present, the write is only performed if the next append
offset is same as the provided value. If not present, the
write is performed at the current end of stream. Specifying
a value for this field is not allowed when calling
AppendRows for the '_default' stream.