ReferenceMap iterator remove violates contract

Out of curiosity I ran Guava's testlib Map tests against the Apache types. This uncovered a contract bug where Iterator.remove() is invalidated by hasNext(), causing its call to no-op due to currentKey becoming null. The isolates case is,

@Test
public void iterator_remove() {
  var map = new ReferenceMap<>();
  map.put(1, 2);
  var iter = map.entrySet().iterator();
  assertTrue(iter.hasNext());
  assertTrue(iter.hasNext());
  assertEquals(iter.next(), 1);
  assertFalse(iter.hasNext());
  iter.remove();
  assertEquals(map, Map.of());
}

Guava's testlib has good coverage for the Collections Framework and might be worth integrating. The simple test case that I wrote is attached.