src/vs/workbench/api/common/extHostExtensionService.ts/AbstractExtHostExtensionService/_applyExtensionsDelta
class AbstractExtHostExtensionService:	private static _applyExtensionsDelta(oldGlobalRegistry: ExtensionDescriptionRegistry, oldMyRegistry: ExtensionDescriptionRegistry, extensionsDelta: IExtensionDescriptionDelta) {
		const globalRegistry = new ExtensionDescriptionRegistry(oldGlobalRegistry.getAllExtensionDescriptions());
		globalRegistry.deltaExtensions(extensionsDelta.toAdd, extensionsDelta.toRemove);

		const myExtensionsSet = extensionIdentifiersArrayToSet(oldMyRegistry.getAllExtensionDescriptions().map(extension => extension.identifier));
		for (const extensionId of extensionsDelta.myToRemove) {
			myExtensionsSet.delete(ExtensionIdentifier.toKey(extensionId));
		}
		for (const extensionId of extensionsDelta.myToAdd) {
			myExtensionsSet.add(ExtensionIdentifier.toKey(extensionId));
		}
		const myExtensions = filterExtensions(globalRegistry, myExtensionsSet);

		return { globalRegistry, myExtensions };
	}