[Ygg2]

> Microservices can't have dependencies between each other otherwise they aren't microservices.

See Hyrum's law:

    Put succinctly, the observation is this:

    With a sufficient number of users of an API,
    it does not matter what you promise in the contract:
    all observable behaviors of your system
    will be depended on by somebody.

One example we bumped spring from 2.1->2.4 (not actual version numbers) Harmless, no? What's worst that can happen?

Failure when doing some but not all operations.

Why? Because some Python/Java micro-services down the operation chain expected null fields to be omitted and the default behavior was changed (between Spring versions) to write null fields instead. Which only occurred on those services that relied on null fields being omitted. Fix was easy but finding the bug was difficult.