Are you sure? It does when I do it.

I don't see any reason why it should be any different.

public class SumSquaredDivisors {
  public static String listSquared(long m, long n) {
    System.out.println("testing123");
    return "";
  }
}

outputs

test1(SumSquaredDivisorsTest)
testing123
  expected:<[[[1, 1], [42, 2500], [246, 84100]]]> but was:<[]>
  
test2(SumSquaredDivisorsTest)
testing123
  expected:<[[[42, 2500], [246, 84100]]]> but was:<[]>
  
test3(SumSquaredDivisorsTest)
testing123
  expected:<[[[287, 84100]]]> but was:<[]>

Maybe the problem isn't in the println itself.

System.out.print("hello"); and System.out.println("hello"); should work in Java without importing.