The first time I tried to launch an API spec on Google Cloud Endpoints, it errored out on missing 'operationId'. Fair enough -- I should have seen that in the tutorial. What I don't understand is if there are any rules or guidelines governing what we assign to operationId and how it affects the environment.
The 'operationId' is mandatory. Beyond that, it needs to be unique within your OpenAPI spec. It is used only to identify the specific operation. It does not have any special effect on your environment.