OpenApiComparer is not implemented

Hello,

My team is using this repository to generate our OpenAPI document, and we started using the OpenApiComparer recently in our project. This method returns a value so we believed it was working until recently when after making a change this still returned an empty list.

After looking at the implementation it's quite clear that this method does nothing but it is documented as being a method that "Compares two OpenApiDocuments and returns a list of differences.".

I believe this method should be removed or should throw instead.

After looking a bit more, there seems to be a valid implementation of this in the vnext branch that was never merged into master.

Inizia leggendo src/Microsoft.OpenApi/Services/OpenApiComparer.cs ed esamina l’implementazione valida nel branch vnext. Determina se la risoluzione prevista consiste nel rimuovere il metodo, fare in modo che generi un’eccezione oppure portare l’implementazione di vnext; il lavoro è completato quando OpenApiComparer non restituisce più silenziosamente un risultato vuoto per un confronto.