Node-red-contrib-google publish

Does anyone know how to format a message for the "google node" (node-red-contrib-google) I am trying the following:
Connection: {{my connections info}}
API: pubsub:v1
Operation: projects.topic.publish

I was able to pull a message but I cant figure out how to publish a message. Here is my best guess at the input message:
"payload": {
"topic": "projects/nchannelqa/topics/a10003.gatewayq"
"messages": [
"data": "SGVsbG8gQ2xvdWQgUHViL1N1YiEgSGVyZSBpcyBteSBtZXNzYWdlIQ"

When I call it I get:
Error: The value for 0 is too small. You passed message_count in the request, but the minimum value is 1.

I just don't know how to specify the message, any ideas?