Resource Leak Checker: false positive from ownership transfer during re-assignment

[kelloggm]

This is a sub-issue of #5969 (where it is described as false positive 1). Consider the following code, which I've checked into the cm-ownership-transfer-at-reassignment branch of my fork:

import org.checkerframework.checker.calledmethods.qual.EnsuresCalledMethods;
import org.checkerframework.checker.mustcall.qual.CreatesMustCallFor;
import org.checkerframework.checker.mustcall.qual.InheritableMustCall;
import org.checkerframework.checker.mustcall.qual.Owning;
import org.checkerframework.checker.nullness.qual.Nullable;

import java.io.IOException;

@InheritableMustCall("disconnect")
public class OwnershipTransferAtReassignment {

  private @Owning @Nullable Node head = null;

  @CreatesMustCallFor("this")
  public boolean add() {
    head = new Node(head);
    return true;
  }

  @EnsuresCalledMethods(value="this.head", methods="disconnect")
  public void disconnect() {
    head.disconnect();
  }

  @InheritableMustCall("disconnect")
  private static class Node {
    @Owning private final @Nullable Node next;

    public Node(@Owning @Nullable Node next) {
      this.next = next;
    }

    @EnsuresCalledMethods(value="this.next", methods="disconnect")
    public void disconnect() {
      next.disconnect();
    }
  }
}

Currently, the checker issues a warning when head is re-assigned at line 16. No warnings should be issued (the re-assignment is safe, because ownership is transferred during the re-assignment to the Node constructor).