api.v0alpha.SendOmniMessageReq(SendOmniMessageReq)

{
    "conversation_sid": 0,
    "payload": {
        "assign_conversation": {
            "user_id": "string",
            "user_name": "string",
            "primary_asm_session_sid": 0
        }
    },
    "campaign_sid": 0,
    "ui_reference_id": "string",
    "channel_type": "CHANNEL_TYPE_EMAIL",
    "message_format": "MESSAGE_FORMAT_UNSPECIFIED"
}