### Question:
PersistedCassandraClusterHealthCheckHistory extends StatePersistedObject<CassandraFrameworkProtos.CassandraClusterHealthCheckHistory> { static boolean objEquals(@Nullable final Object o1, @Nullable final Object o2) { return o1 == null && o2 == null || !(o1 == null || o2 == null) && o1.equals(o2); } PersistedCassandraClusterHealthCheckHistory(
        @NotNull final State state
    ); @NotNull List<CassandraFrameworkProtos.HealthCheckHistoryEntry> entries(); @NotNull List<CassandraFrameworkProtos.HealthCheckHistoryEntry> entriesForExecutor(@NotNull final String executorId); @Nullable CassandraFrameworkProtos.HealthCheckHistoryEntry last(@NotNull final String executorId); void record(@NotNull final String executorId, final long timestamp, @NotNull final CassandraFrameworkProtos.HealthCheckDetails healthCheckDetails);  }### Answer:
@Test public void testObjEquals() throws Exception { assertTrue(PersistedCassandraClusterHealthCheckHistory.objEquals(null, null)); assertFalse(PersistedCassandraClusterHealthCheckHistory.objEquals(null, "")); assertFalse(PersistedCassandraClusterHealthCheckHistory.objEquals("", null)); assertTrue(PersistedCassandraClusterHealthCheckHistory.objEquals("1", "1")); assertTrue(PersistedCassandraClusterHealthCheckHistory.objEquals(1, 1)); assertFalse(PersistedCassandraClusterHealthCheckHistory.objEquals("1", "2")); assertFalse(PersistedCassandraClusterHealthCheckHistory.objEquals(1, 2)); }