@Test
void set() {

    session.set("key", "value");
    assertThat(session.changedFields).containsOnly("key");
    assertThat(session.get("key")).get().isEqualTo("value");
    session.set("key", null);
    assertThat(session.changedFields).containsOnly("key");
    assertThat(session.get("key")).isNotPresent();
}