Write JSON values to the distributed ledger. The body is treated as an object of key-value pairs, with the values getting written to the distributed ledger and replaced with tokens in the response. There is a per-request limit of 1024 key-value pairs, with no value allowed to be greater than 3kb in size. If the size of the batch is greater than 500kb, the request will be rejected. The PostBatch operation offers read-after-write consistency and each token is available when the response is sent.