If you are on the java platform I have an unpopular recommendation: get familiar with OSGi. Its specs, its history and its core concepts. The learning path you go will teach you a lot about how to build systems, how to think about api design, modularisation and standards (compared to one-off company owned tech). Its almost certainly makes you a better developer/thinker.
The true question is: are the values that OSGi stands for (still) reasonable?
The values are: modularity as core concept at build and runtime, low footprint adaptive services and vendor-agnostic specification.
Now, OSGi may have a poor image in the current Microservices/cloud vendor driven bubble. But let’s step a bit back and ask:
1. isn’t constructing software from building-blocks useful? What’s up with reuse, synergy, not throw away software?
2. Wouldn’t services be useful that don’t just die but reconfigure (adapt) when upstream dependencies change/go away?
3. Is time to market really the best incentive these days? What’s up with making sure software is constructed with security and privacy in mind? What about assuming your startup isn’t sold (sell and forget) but you need to evolve it?
So, incidentally those qualities are part of the OSGi values made up about 20 years ago. If not OSGi (a messenger of values), wouldn’t the values make more sense now more than ever?