For component definitions that are declared but never used, a warning would be helpful. The following description is from Ted Epstein for support ticket #470:
The editor should automatically disable this warning by default if the file has an empty paths object (denoted as open+close curly braces as the value of the paths object). In this case, it's clear that the purpose of this OpenAPI document is to hold components that can be referenced from other documents.
The editor should have some context to determine whether those components are referenced. In API Studio, we have a project scope and a workspace scope that could be natural boundaries, and if we don't see references to a given component within those boundaries, then it can be useful to flag those components as unreferenced.
The editor should provide a way to disable that warning, in case the components are referenced from outside of the validation scope.
Thanks for the suggestion, Joe! We'll add this to our backlog and plan address it along with some other improvements to OpenAPI validation.