How to share events code in a microservice architecture

I'm working on a "microservice-like" architecture. Each microservice can fire some events which are identified by an event code. At the moment, the code of the event triggered is an hard coded const string declared inside the microservice that fire the event. My problem is that each microservice that want to subscribe to this event must duplicate this event code string. This is error prone especially when an event code is renamed because all microservices that subscribed to this event code need to be changed accordingly... which is very bad.

I see the possible alternatives:

• Declare the event code only in the microservice that fire the event. Let the consumers microservices directly access to the code declared in the microservice that fire the event. In this case, the event is declared once but it creates a source code dependency between microservices... which is bad.

• Create a source file (outside all microservices) that contains all the events code of all the application. This source file is shared by all microservices. In this case, each event is declared once but it creates a global dependency for all microservices which is against the single responsability principle... which is bad.

How do you tackle this problem ?