UnnecessarilyFullyQualified - Error Prone

Prefer using imported names to refer to classes, unless a qualified name is necessary to disambiguate two classes with the same name.

That is, prefer this:

java

import java.util.ArrayList;
import java.util.List;

class Test {
  List<String> names = new ArrayList<>();
}

instead of this:

java

class Test {
  java.util.List<String> names = new java.util.ArrayList<>();
}