*     FIRST_LETTER_MULTIMAP.put('a', "pple");
   *     FIRST_LETTER_MULTIMAP.put('a', "sparagus");
   *     FIRST_LETTER_MULTIMAP.put('c', "arrot");
   *     FIRST_LETTER_MULTIMAP.put('c', "herry");
   * }
   * }
   *
   * <p>To collect to an {@link ImmutableMultimap}, use either {@link
   * ImmutableSetMultimap#toImmutableSetMultimap} or {@link
   * ImmutableListMultimap#toImmutableListMultimap}.
   *

    }

    @Test
    public void test_getWords() throws Exception {
        List<String> words = new ArrayList<>();
        words.add("apple");
        words.add("banana");
        words.add("cherry");

        PopularWordsResponse response = new PopularWordsResponse("test-index", 100, words, 10, new ArrayList<>());

        assertNotNull(response.getWords());
        assertEquals(3, response.getWords().size());

    }

    @Test
    @DisplayName("Should join with multi-character delimiter")
    void testJoinWithMultiCharDelimiter() {
        String result = StringUtil.join(" - ", "apple", "banana", "cherry");
        assertEquals("apple - banana - cherry", result);
    }

    @Test
    @DisplayName("Should handle null delimiter by inserting 'null' string")
    void testJoinWithNullDelimiter() {

import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests com.google.common.base.Suppliers.
 *
 * @author Laurence Gonsalves
 * @author Harry Heymann
 */
@NullMarked
@GwtCompatible
public class SuppliersTest extends TestCase {

  static class CountingSupplier implements Supplier<Integer> {
    int calls = 0;

    @Override

import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests com.google.common.base.Suppliers.
 *
 * @author Laurence Gonsalves
 * @author Harry Heymann
 */
@NullMarked
@GwtCompatible
public class SuppliersTest extends TestCase {

  static class CountingSupplier implements Supplier<Integer> {
    int calls = 0;

    @Override

import org.jspecify.annotations.Nullable;

/**
 * Useful suppliers.
 *
 * <p>All methods return serializable suppliers as long as they're given serializable parameters.
 *
 * @author Laurence Gonsalves
 * @author Harry Heymann
 * @since 2.0
 */
@GwtCompatible
public final class Suppliers {
  private Suppliers() {}

  /**
   * Returns a new supplier which is the composition of the provided function and supplier. In other

    sequences.add(new StringBuilder("henry"));
    sequences.add(new StringBuilder("apple"));
    sequences.add("lemon");

    assertEquals(3, Iterables.indexOf(sequences, STARTSWITH_A));
  }

  public void testIndexOf_genericPredicate2() {
    List<String> sequences = Lists.newArrayList("bob", "charlie", "henry", "apple", "lemon");

import java.util.ArrayList;
import java.util.List;

/**
 * A class for arithmetic on values of type {@code BigInteger}.
 *
 * <p>The implementations of many methods in this class are based on material from Henry S. Warren,
 * Jr.'s <i>Hacker's Delight</i>, (Addison Wesley, 2002).
 *
 * <p>Similar functionality for {@code int} and for {@code long} can be found in {@link IntMath} and
 * {@link LongMath} respectively.
 *

 * names</a> such as {@code 网络.cn} are supported, as are the equivalent <a
 * href="http://en.wikipedia.org/wiki/Internationalized_domain_name">IDNA Punycode-encoded</a>
 * versions.
 *
 * @author Catherine Berry
 * @since 5.0
 */
@GwtCompatible
@Immutable
public final class InternetDomainName {

  private static final CharMatcher DOTS_MATCHER = CharMatcher.anyOf(".\u3002\uFF0E\uFF61");

            .build();
    CollectorTester.of(collector, equivalence)
        .expectCollects(empty)
        .expectCollects(filled, "banana", "apple", "carrot", "asparagus", "cherry");
  }

  public void testEmptyMultimapReads() {
    ImmutableListMultimap<String, Integer> multimap = ImmutableListMultimap.of();
    assertFalse(multimap.containsKey("foo"));