Method register

packages/core/ui/core/properties/index.ts:342–348

(cls: { prototype: T })

	}

	public register(cls: { prototype: T }): void {
		if (this.registered) {
			throw new Error(`Property ${this.name} already registered.`);
		}
		this.registered = true;
		Object.defineProperty(cls.prototype, this.name, this);
	}

	public isSet(instance: T): boolean {
		return this.key in instance;