Collection.isEmpty() should be used to test for emptiness

There are ~40 checks for whether a collection is or is not empty using the Collection.size() and a less than or greater than 0.

It is cleaner to use the Collection.isEmpty()

Refer to sonar

https://ci.openmrs.org/sonar/drilldown/issues/1865?severity=CRITICAL

to find the related code.

The rule that is violated is "Collection.isEmpty() should be used to test for emptiness" which can be found under the severity critical.