import java.util.Stack;
import org.checkerframework.checker.initialization.qual.*;
import org.checkerframework.checker.nullness.qual.*;
import org.checkerframework.dataflow.qual.*;

public final class InitializedField {
  private Stack<Object> stack;

  InitializedField() {
    stack = new Stack<Object>();
    iPeek();
  }

  @RequiresNonNull("stack")
  public Object iPeek(@UnknownInitialization InitializedField this) {
    return stack.peek();
  }

  public static void testJavaClass(InitializedField initField) {
    initField.iPeek();
  }
}