DeployRequest represents and contains the data needed to deploy an application Note that the overall application configuration (instances, configurations, EVs) is already known server side, through AppCreate/AppUpdate requests. This request not only comes with the image to deploy, but also the information where the sources of that image came from.
AppRef references an App by name and namespace
ApplicationOrigin is the part of the manifest describing the origin of the application (sources). At most one of the fields may be specified / not empty.
StageRef references a staging run by ID, currently randomly generated for each POST to the staging endpoint