// Different input
        assertFalse(item1.equals(item3));

        // Same id and input
        assertTrue(item1.equals(item4));

        // Null object
        assertFalse(item1.equals(null));

        // Different class
        assertFalse(item1.equals("word"));

        // Symmetry
        assertTrue(item1.equals(item2));
        assertTrue(item2.equals(item1));
    }

        "Two Maps should not be equal if exactly one of them contains a null value.",
        getMap().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_smallerMap() {
    Collection<Entry<K, V>> fewerEntries = getSampleEntries(getNumEntries() - 1);
    assertFalse(
        "Maps of different sizes should not be equal.", getMap().equals(newHashMap(fewerEntries)));
  }

            // Test null vs null
            assertTrue(auth1.equals(new NtlmPasswordAuthenticator("domain", "user", (String) null)));

            // Test null vs empty
            assertFalse(auth1.equals(auth2));

            // Test null vs password
            assertFalse(auth1.equals(auth3));

            // Test empty vs password
            assertFalse(auth2.equals(auth3));

      assertTrue(item + " must not be Object#equals to null", !item.equals(null));
      assertTrue(
          item + " must not be Object#equals to an arbitrary object of another class",
          !item.equals(NotAnInstance.EQUAL_TO_NOTHING));
      assertTrue(item + " must be Object#equals to itself", item.equals(item));
      assertEquals(

      !"Connection".equals(fieldName, ignoreCase = true) &&
        !"Keep-Alive".equals(fieldName, ignoreCase = true) &&
        !"Proxy-Authenticate".equals(fieldName, ignoreCase = true) &&
        !"Proxy-Authorization".equals(fieldName, ignoreCase = true) &&
        !"TE".equals(fieldName, ignoreCase = true) &&
        !"Trailers".equals(fieldName, ignoreCase = true) &&

        "Two Maps should not be equal if exactly one of them contains a null value.",
        getMap().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_smallerMap() {
    Collection<Entry<K, V>> fewerEntries = getSampleEntries(getNumEntries() - 1);
    assertFalse(
        "Maps of different sizes should not be equal.", getMap().equals(newHashMap(fewerEntries)));
  }

        // Act & Assert
        assertTrue(left.equals(right), "Blobs with equal content should be equal");
        assertTrue(right.equals(left), "Equality should be symmetric for identical content");
    }

    // Demonstrates observed equals() asymmetry when this is shorter than argument
    @Test
    @DisplayName("equals: this shorter but same prefix -> true (observed behavior)")

        assertTrue(item1.equals(item3));

        // Different input value
        assertFalse(item1.equals(item4));

        // Null and different class
        assertFalse(item1.equals(null));
        assertFalse(item1.equals("string"));
        assertFalse(item1.equals(new Object()));
    }

    @Test
    public void test_equals_withNewInput() {

      assertTrue(item + " must not be Object#equals to null", !item.equals(null));
      assertTrue(
          item + " must not be Object#equals to an arbitrary object of another class",
          !item.equals(NotAnInstance.EQUAL_TO_NOTHING));
      assertTrue(item + " must be Object#equals to itself", item.equals(item));
      assertEquals(

        // Support upgrades: 4.0.0 → 4.1.0, 4.0.0 → 4.2.0, 4.1.0 → 4.2.0
        if (MODEL_VERSION_4_0_0.equals(fromVersion)) {
            return MODEL_VERSION_4_1_0.equals(toVersion) || MODEL_VERSION_4_2_0.equals(toVersion);
        }
        if (MODEL_VERSION_4_1_0.equals(fromVersion)) {
            return MODEL_VERSION_4_2_0.equals(toVersion);
        }

        return false;
    }

    /**