Getting schema on a splitter transform (say null splitter) doesn't return `portSchemas` in the response which UI uses to update the schema for the splitter plugin.
Setting this as critical as there is no way user can manually type in multiple schemas in the UI.
Attached a gif for reference.
Fixed a bug that caused splitter transforms to be unable to fetch their output ports and schemas.
This was removed from the backend because it's not used there and it's duplicate information (same information is in the outputPorts field). Will put it back since it is required in the stage validation call, where there are not output connections.