src/vs/workbench/browser/parts/editor/textDiffEditor.ts/TextDiffEditor/toEditorViewStateResource
class TextDiffEditor:	protected override toEditorViewStateResource(modelOrInput: IDiffEditorModel | EditorInput): URI | undefined {
		let original: URI | undefined;
		let modified: URI | undefined;

		if (modelOrInput instanceof DiffEditorInput) {
			original = modelOrInput.original.resource;
			modified = modelOrInput.modified.resource;
		} else if (!isEditorInput(modelOrInput)) {
			original = modelOrInput.original.uri;
			modified = modelOrInput.modified.uri;
		}

		if (!original || !modified) {
			return undefined;
		}

		// create a URI that is the Base64 concatenation of original + modified resource
		return URI.from({ scheme: 'diff', path: `${multibyteAwareBtoa(original.toString())}${multibyteAwareBtoa(modified.toString())}` });
	}