* elementSet()}, do not support {@code remove()}. However, all other multiset methods supported
   * by {@code unfiltered} are supported by the returned multiset. When given an element that
   * doesn't satisfy the predicate, the multiset's {@code add()} and {@code addAll()} methods throw
   * an {@link IllegalArgumentException}. When methods such as {@code removeAll()} and {@code

 *
 * <p>The following types of methods are provided:
 *
 * <ul>
 *   <li>chaining methods which return a new {@code FluentIterable} based in some way on the
 *       contents of the current one (for example {@link #transform})
 *   <li>element extraction methods which facilitate the retrieval of certain elements (for example
 *       {@link #last})

 *
 * <p>The following types of methods are provided:
 *
 * <ul>
 *   <li>chaining methods which return a new {@code FluentIterable} based in some way on the
 *       contents of the current one (for example {@link #transform})
 *   <li>element extraction methods which facilitate the retrieval of certain elements (for example
 *       {@link #last})

   * elementSet()}, do not support {@code remove()}. However, all other multiset methods supported
   * by {@code unfiltered} are supported by the returned multiset. When given an element that
   * doesn't satisfy the predicate, the multiset's {@code add()} and {@code addAll()} methods throw
   * an {@link IllegalArgumentException}. When methods such as {@code removeAll()} and {@code

}
```

## 🏗️ Architecture & Design Patterns

### Core Design Principles
CoreLib follows a **utility-class pattern** where most functionality is exposed through static methods:

- **Assertion-based validation** - All methods validate inputs using `AssertionUtil.assertArgumentNotNull()` and `AssertionUtil.assertArgumentNotEmpty()`

    testDecodes(ignoreCase, "666F6F626172", "foobar");
    testDecodes(ignoreCase, "666f6f626172", "foobar");
    testDecodes(ignoreCase, "666F6f626172", "foobar");
  }

  // order the methods are called should not matter
  public void testBase16IgnoreCaseLowerCase() {
    BaseEncoding ignoreCase = base16().ignoreCase().lowerCase();
    assertThat(ignoreCase).isNotSameInstanceAs(base16());

import java.util.Arrays;
import java.util.Comparator;

/**
 * Static utility methods pertaining to {@code long} primitives that interpret values as
 * <i>unsigned</i> (that is, any negative value {@code x} is treated as the positive value {@code
 * 2^64 + x}). The methods for which signedness is not an issue are in {@link Longs}, as well as
 * signed versions of methods for which signedness is an issue.
 *

    // The following legacy hashing function methods have been covered by unit testing already.
    ImmutableSet<String> legacyHashingMethodNames =
        ImmutableSet.of("murmur2_64", "fprint96", "highwayFingerprint64", "highwayFingerprint128");
    return method.getReturnType().equals(HashFunction.class) // must return HashFunction
        && Modifier.isPublic(method.getModifiers()) // only the public methods

  val subjectPublicKey: BitString,
)

@IgnoreJRERequirement // As of AGP 3.4.1, D8 desugars API 24 hashCode methods.
internal data class Extension(
  val id: String,
  val critical: Boolean,
  val value: Any?,
)

@IgnoreJRERequirement // As of AGP 3.4.1, D8 desugars API 24 hashCode methods.
internal data class BasicConstraints(
  /** True if this certificate can be used as a Certificate Authority (CA). */

import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;
import org.jspecify.annotations.Nullable;

/**
 * Abstract test case parent for anything implementing {@link ListenableFuture}. Tests the two get
 * methods and the addListener method.
 *
 * @author Sven Mawson
 * @since 10.0
 */
@GwtIncompatible
public abstract class AbstractListenableFutureTest extends TestCase {

  protected CountDownLatch latch;