Optional. The current etag of the Cluster. If an etag is provided and does not match the current etag of the Cluster, upgrade will be blocked and an ABORTED error will be returned.

Optional. An optional request ID to identify requests. Specify a unique request ID so that if you must retry your request, the server ignores the request if it has already been completed. The server guarantees that for at least 60 minutes since the first request. For example, consider a situation where you make an initial request and the request times out. If you make the request again with the same request ID, the server can check if the original operation with the same request ID was received, and if so, ignores the second request. This prevents clients from accidentally creating duplicate commitments. The request ID must be a valid UUID with the exception that zero UUID is not supported (00000000-0000-0000-0000-000000000000).

Optional. If set, performs request validation, for example, permission checks and any other type of validation, but does not actually execute the create request.

Required. The version the cluster is going to be upgraded to.