Channel containing the message to be updated. A channel ID can be found at the bottom of the channel’s details screen.
Message Blocks
A JSON-based array of structured blocks, presented as a URL-encoded string. If you don’t include this field, the message’s previous blocks will be retained. To remove previous blocks, include an empty array for this field.
Message Text
New text for the message, using the default formatting rules. It’s not required when presenting blocks or attachments.
Timestamp
Timestamp of the message to be updated. for example - ‘1234567890.123456’.