Why is this an issue?

Java’s import mechanism allows the use of simple class names. Therefore, using a class' fully qualified name in a file that imports the class is redundant and confusing.

Noncompliant code example

import java.util.List;
import java.sql.Timestamp;

//...

java.util.List<String> myList;  // Noncompliant
java.sql.Timestamp tStamp; // Noncompliant

Compliant solution

import java.util.List;
import java.sql.Timestamp;

//...

List<String> myList;
Timestamp tStamp;