StopwordsItem item1 = new StopwordsItem(1, "test");
        StopwordsItem item2 = new StopwordsItem(1, "test");

        item1.setNewInput("updated");
        item2.setNewInput("different");

        // Should still be equal based on original input
        assertTrue(item1.equals(item2));
    }

    @Test
    public void test_equals_withNullInput() {

        CharMappingItem item2 = new CharMappingItem(2L, inputs2, "output");
        CharMappingItem item3 = new CharMappingItem(3L, inputs3, "output");
        CharMappingItem item4 = new CharMappingItem(4L, inputs1, "different");

        // Same inputs and output should have same hash code
        assertEquals(item1.hashCode(), item2.hashCode());

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

    @Test
    public void test_equals_withNullInput() {
        // Test equals with null input - should not throw, uses null-safe comparison
        ProtwordsItem item1 = new ProtwordsItem(1, null);
        ProtwordsItem item2 = new ProtwordsItem(2, null);

        readings2[0] = new String[] { "next" };
        SuggestItem item2 = new SuggestItem(new String[] { "次" }, readings2, new String[] { "content" }, 1, 0, -1, new String[] { "tag1" },
                new String[] { SuggestConstants.DEFAULT_ROLE }, null, SuggestItem.Kind.DOCUMENT);
        suggester.indexer().index(item2);
        suggester.refresh();

        OptionalEntity<CharMappingItem> result2 = charMappingFile.get(2L);
        assertTrue(result2.isPresent());
        CharMappingItem item2 = result2.get();
        assertEquals(2L, item2.getId());
        assertArrayEquals(new String[] { "d", "e" }, item2.getInputs());
        assertEquals("f", item2.getOutput());

        OptionalEntity<CharMappingItem> result3 = charMappingFile.get(3L);
        assertFalse(result3.isPresent());
    }

        SuggestItem item2 = new SuggestItem(new String[] { "テスト" }, readings, new String[] { "content" }, 2, 0, -1, new String[] { "tag2" },
                new String[] { SuggestConstants.DEFAULT_ROLE }, null, SuggestItem.Kind.DOCUMENT);

        SuggestItem[] mergedItems = writer.mergeItems(new SuggestItem[] { item1, item2 });

        assertNotNull(mergedItems);

        assertTrue(result.isPresent());
        assertEquals(testValue, result.get());
    }

    @Test
    public void test_ofNullable_withList() {
        List<String> testValue = Arrays.asList("item1", "item2", "item3");
        OptionalEntity<List<String>> result = OptionalUtil.ofNullable(testValue);

        assertNotNull(result);
        assertTrue(result.isPresent());
        assertEquals(testValue, result.get());

    }

    @Test
    public void test_register_nonEntityList() {
        RenderData data = new RenderData();
        List<String> stringList = Arrays.asList("item1", "item2", "item3");

        RenderDataUtil.register(data, "strings", stringList);

        Object result = data.getDataMap().get("strings");

                builder.field("value", 123);
                builder.field("enabled", true);
                builder.startArray("items");
                builder.value("item1");
                builder.value("item2");
                builder.endArray();
                builder.startObject("nested");
                builder.field("inner", "value");
                builder.endObject();
                builder.endObject();

        final List<String> items = List.of("item1", "item2", "item3");
        chatApiManager.sendSseEvent(writer, "test", Map.of("items", items));

        final String output = stringWriter.toString();
        assertTrue(output.contains("event: test"));
        assertTrue(output.contains("["));
        assertTrue(output.contains("item1"));
        assertTrue(output.contains("item2"));
        assertTrue(output.contains("item3"));
    }