NRefactory extends the roslyn code actions to support features from NRefactory 5.

The NRefactoryCodeAction class is the base of all NRefactory code actions. It adds a DiagnosticSeverity and a TextSpan where this code action is activated.

The DocumentChangeAction is the base class for doing changes inside a single document. NRefactory needs control over the post processing to support NRefactory 5 features.

Code actions should always be generated with the CodeActionFactory