chat.postEphemeral missing parameters

[NickDarvey]

Description

Operation chat.postEphemeral (line 7184) does not specify all of the parameters as declared in the text docs, specifically:

• icon_emoji
• icon_url
• username

What type of issue is this? (place an x in one of the [ ])

• [x] bug
• [ ] enhancement (feature request)
• [ ] question
• [ ] documentation related
• [ ] testing related
• [ ] discussion

Requirements (place an x in each of the [ ])

• [x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.
• [x] I've searched for any related issues and avoided creating a duplicate issue.