SessionState { public synchronized boolean contains(final T item) { return items.contains(idSupplier.applyAsLong(item)); } SessionState(final Tenant tenant, final ToLongFunction<T> idSupplier, final String key);  SessionState(final Tenant tenant, final Collection<T> retain, final ToLongFunction<T> idSupplier,
            final String key); synchronized void put(final T item); synchronized boolean contains(final T item); @Override String toString();  }
@Test @DisplayName("stores elements.") void putIntoEmpty() { assertThat(state.contains(INITIAL_LOAN)).isTrue(); }