}

    public void test_normalize_null() {
        String enc;

        enc = null;
        assertNull(encodingHelper.normalize(enc));

        enc = "";
        assertNull(encodingHelper.normalize(enc));

        enc = " ";
        assertNull(encodingHelper.normalize(enc));
    }

    public void test_normalize_default() {
        String enc;

        // Arrange & Act
        SMBProtocolDecodingException ex = new SMBProtocolDecodingException();

        // Assert state
        assertNull(ex.getMessage(), "Default constructor should have null message");
        assertNull(ex.getCause(), "Default constructor should have null cause");
        assertTrue(ex instanceof CIFSException, "Should be a CIFSException subtype");

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.ArgumentMatchers.anyInt;
import static org.mockito.ArgumentMatchers.anyString;
import static org.mockito.Mockito.mock;

    for (BoundType type : BoundType.values()) {
      assertNull(sortedMultiset.headMultiset(e0(), type).lastEntry());
      assertNull(sortedMultiset.tailMultiset(e0(), type).firstEntry());
    }
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMultisetLast() {
    assertNull(sortedMultiset.lastEntry());
    assertThrows(
        NoSuchElementException.class, () -> assertNull(sortedMultiset.elementSet().last()));
  }

import static org.junit.jupiter.api.Assertions.assertArrayEquals;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

        Kerb5Authenticator auth = new Kerb5Authenticator((Subject) null);

        // User accessors
        assertNull(auth.getUser());
        auth.setUser(null);
        assertNull(auth.getUser());
        auth.setUser("");
        assertEquals("", auth.getUser());

        // Realm accessors
        assertNull(auth.getRealm());
        auth.setRealm("EXAMPLE.COM");
        assertEquals("EXAMPLE.COM", auth.getRealm());

        assertNull(config.getNetbiosHostname());
        assertNull(config.getLocalAddr());
        assertNull(config.getBroadcastAddress());
        assertNull(config.getResolveOrder());
        assertNotNull(config.getWinsServers());
        assertEquals(0, config.getWinsServers().length);
        assertEquals(0, config.getNetbiosLocalPort());
        assertNull(config.getNetbiosLocalAddress());

    assertNull(map.get(TypeToken.of(Integer.class)));
    assertNull(map.getInstance(Integer.class));

    map.putInstance(Long.class, null);
    assertTrue(map.containsKey(TypeToken.of(Long.class)));
    assertTrue(map.entrySet().contains(immutableEntry(TypeToken.of(Long.class), null)));
    assertNull(map.get(TypeToken.of(Long.class)));
    assertNull(map.getInstance(Long.class));
  }

    } else {
      assertThrows(UnsupportedOperationException.class, () -> table.clear());
    }
  }

  public void testPut() {
    assertNull(table.put("foo", 1, cellValue('a')));
    assertNull(table.put("bar", 1, cellValue('b')));
    assertNull(table.put("foo", 3, cellValue('c')));
    assertEquals((Character) 'a', table.put("foo", 1, cellValue('d')));
    assertEquals((Character) 'd', table.get("foo", 1));

    try {
      assertNull(
          "remove(null) should return null or throw NullPointerException", getMap().remove(null));
    } catch (NullPointerException tolerated) {
    }
    expectUnchanged();
  }

  @MapFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_KEY_QUERIES})
  public void testRemove_nullSupportedMissing() {
    assertNull("remove(null) should return null", getMap().remove(null));