Expanding lambda expressions to anonymous classes may be useful if you need to implement other methods inside an anonymous class or if you need to downgrade to one of the previous Java versions.
Example:
s -> System.out.println(s)
After the quick-fix is applied:
new Consumer<String>() {
@Override
public void accept(String s) {
System.out.println(s);
}
}
This inspection is available in Java 8 and later.