BiPredicate<ImmutableSetMultimap<?, ?>, ImmutableSetMultimap<?, ?>> equivalence =
        Equivalence.equals()
            .onResultOf(
                (ImmutableSetMultimap<?, ?> mm) ->
                    ImmutableListMultimap.copyOf(mm).asMap().entrySet().asList())
            .and(Equivalence.equals());
    CollectorTester.of(collector, equivalence)
        .expectCollects(ImmutableSetMultimap.of())
        .expectCollects(

Integer nullValue = IntegerConversionUtil.toInteger(null);     // Returns null
Boolean flag = BooleanConversionUtil.toBoolean("true");        // Returns true
Date date = DateConversionUtil.toDate("2023-12-25", "yyyy-MM-dd");

// Primitive conversions with default values
int primitiveInt = IntegerConversionUtil.toPrimitiveInt(value, "0");  // Default to 0 if null
```

### Collection Utilities with Java 21 Support
```java

    /**
     * The ndjson extension.
     */
    public static final String NDJSON_EXTENTION = ".ndjson";

    private static final DateTimeFormatter ISO_8601_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSS");

    @Resource
    private AsyncManager asyncManager;

    @Resource
    private WebConfigBhv webConfigBhv;

    @Resource
    private FileConfigBhv fileConfigBhv;