- **Memory efficient** - Specialized collections like `LruHashMap` and `ArrayMap` for memory-conscious applications
- **Java 21 features** - Switch expressions and pattern matching for reduced overhead

## 🧪 Building and Testing

### Development Setup
```bash
# Clone the repository
git clone https://github.com/codelibs/corelib.git
cd corelib

# Compile the project
mvn clean compile

 *       allocating garbage).
 * </ul>
 *
 * <p>Disadvantages compared to {@code long[]}:
 *
 * <ul>
 *   <li>Memory footprint has a fixed overhead (about 24 bytes per instance).
 *   <li><i>Some</i> construction use cases force the data to be copied (though several construction
 *       APIs are offered that don't).

 *       allocating garbage).
 * </ul>
 *
 * <p>Disadvantages compared to {@code int[]}:
 *
 * <ul>
 *   <li>Memory footprint has a fixed overhead (about 24 bytes per instance).
 *   <li><i>Some</i> construction use cases force the data to be copied (though several construction
 *       APIs are offered that don't).

  // There are a few design constraints to consider
  // * We want to be responsive to small timeouts, unpark() has non trivial latency overheads (I
  //   have observed 12 micros on 64-bit linux systems to wake up a parked thread). So if the
  //   timeout is small we shouldn't park(). This needs to be traded off with the cpu overhead of
  //   spinning, so we use SPIN_THRESHOLD_NANOS which is what AbstractQueuedSynchronizer uses for
  //   similar purposes.

  // There are a few design constraints to consider
  // * We want to be responsive to small timeouts, unpark() has non trivial latency overheads (I
  //   have observed 12 micros on 64-bit linux systems to wake up a parked thread). So if the
  //   timeout is small we shouldn't park(). This needs to be traded off with the cpu overhead of
  //   spinning, so we use SPIN_THRESHOLD_NANOS which is what AbstractQueuedSynchronizer uses for
  //   similar purposes.

  }

  static void clearInterrupt() {
    Thread.interrupted();
  }

  /**
   * Retrieves the result of a {@code Future} known to be done but uses the {@code get(long,
   * TimeUnit)} overload in order to test that method.
   */
  static <V extends @Nullable Object> V getDoneFromTimeoutOverload(Future<V> future)
      throws ExecutionException {

    assertTrue(set instanceof SingletonImmutableSet);
    assertEquals(Lists.newArrayList("a"), new ArrayList<>(set));
  }

  public void testCreation_oneDuplicate() {
    // now we'll get the varargs overload
    @SuppressWarnings("DistinctVarargsChecker") // deliberately testing deduplication
    ImmutableSet<String> set =
        ImmutableSet.of("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "a");

    assertTrue(set instanceof SingletonImmutableSet);
    assertEquals(Lists.newArrayList("a"), new ArrayList<>(set));
  }

  public void testCreation_oneDuplicate() {
    // now we'll get the varargs overload
    @SuppressWarnings("DistinctVarargsChecker") // deliberately testing deduplication
    ImmutableSet<String> set =
        ImmutableSet.of("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "a");

    // ambiguous without the cast to Object because the boxed predicate prevents any overload from
    // being selected in phase 1
    checkState(boxedBoolean, "", (Object) boxedLong);

    // ternaries introduce their own problems. because of the ternary (which requires a boxing
    // operation) no overload can be selected in phase 1.  and in phase 2 it is ambiguous since it

    // ambiguous without the cast to Object because the boxed predicate prevents any overload from
    // being selected in phase 1
    checkState(boxedBoolean, "", (Object) boxedLong);

    // ternaries introduce their own problems. because of the ternary (which requires a boxing
    // operation) no overload can be selected in phase 1.  and in phase 2 it is ambiguous since it