REST api endpoints should expose metrics for application monitoring

[dgroup]

Summary

Key	Value
Rule	RestEndpointsWithoutExposedMetrics
Ruleset	io/github/dgroup/arch4u/pmd/arch4u-ruleset.xml
Category	Design
Framework	io.micrometer:micrometer-core, org.openapitools:openapi-generator
Since	0.1.0
Incidents in past at my experience	10+

Why?

Do we like it or not the REST API is a de-facto standard for API development and mostly a huge number of apps have it.
As soon as the app went go-live the API monitoring will become one of the first questions and loading transparency, tps, etc.

@RestController
public class MyTypicalRestController {

   @GetMapping("/foo")    //violation
   public Foo getFoo() {
      //...
   }

   @Timed
   @GetMapping("/bar")    // ok, because annotation @Timed is present
   public Foo getBar() {
      //...
   }
}

The current rule is oriented for apps that are using micrometer.io framework.