StringBuilder buf = new StringBuilder();

        monitorTarget.append(buf, "key1", () -> "value1");
        buf.append(",");
        monitorTarget.append(buf, "key2", () -> 123);
        buf.append(",");
        monitorTarget.append(buf, "key3", () -> null);

        assertEquals("\"key1\":\"value1\",\"key2\":123,\"key3\":null", buf.toString());
    }

    // Test append with empty string
    @Test

    for (LoadingCache<Key, String> cache : caches()) {
      Key key1 = new Key(1);
      String value1 = key1.toString();
      Key key2 = new Key(2);
      String value2 = key2.toString();
      assertThat(cache.getUnchecked(key1)).isSameInstanceAs(value1);
      assertThat(cache.getUnchecked(key2)).isSameInstanceAs(value2);
      assertThat(cache.asMap().keySet()).isEqualTo(ImmutableSet.of(key1, key2));

    for (LoadingCache<Key, String> cache : caches()) {
      Key key1 = new Key(1);
      String value1 = key1.toString();
      Key key2 = new Key(2);
      String value2 = key2.toString();
      assertThat(cache.getUnchecked(key1)).isSameInstanceAs(value1);
      assertThat(cache.getUnchecked(key2)).isSameInstanceAs(value2);
      assertThat(cache.asMap().keySet()).isEqualTo(ImmutableSet.of(key1, key2));

        facetQueryView.addQuery("key1", "query1");
        assertEquals(1, facetQueryView.getQueryMap().size());
        assertEquals("query1", facetQueryView.getQueryMap().get("key1"));

        facetQueryView.addQuery("key2", "query2");
        assertEquals(2, facetQueryView.getQueryMap().size());
        assertEquals("query2", facetQueryView.getQueryMap().get("key2"));

        // Test overwriting existing key

        sourceMap.put("key1", "value1");
        sourceMap.put("key2", 123);
        sourceMap.put("key3", true);
        event.setSourceMap(sourceMap);

        Map<String, Object> result = event.toSource();
        assertNotNull(result);
        assertEquals(3, result.size());
        assertEquals("value1", result.get("key1"));
        assertEquals(123, result.get("key2"));

   *
   * <ul>
   *   <li>To output a separate entry for each key-value pair, pass {@code multimap.entries()} to a
   *       {@code MapJoiner} method that accepts entries as input, and receive output of the form
   *       {@code key1=A&key1=B&key2=C}.
   *   <li>To output a single entry for each key, pass {@code multimap.asMap()} to a {@code

   *
   * <ul>
   *   <li>To output a separate entry for each key-value pair, pass {@code multimap.entries()} to a
   *       {@code MapJoiner} method that accepts entries as input, and receive output of the form
   *       {@code key1=A&key1=B&key2=C}.
   *   <li>To output a single entry for each key, pass {@code multimap.asMap()} to a {@code

    String key1 = "key1";
    String key2 = "key2";

    assertThat(
            cache.get(
                key1,
                new CacheLoader<String, String>() {
                  @Override
                  public String load(String key) throws Exception {
                    return cache.get(key2, identityLoader()); // loads a different key, should work
                  }

    String key1 = "key1";
    String key2 = "key2";

    assertThat(
            cache.get(
                key1,
                new CacheLoader<String, String>() {
                  @Override
                  public String load(String key) throws Exception {
                    return cache.get(key2, identityLoader()); // loads a different key, should work
                  }

        // Test initial null map
        crawlingInfoHelper.putToInfoMap("key1", "value1");
        assertNotNull(crawlingInfoHelper.infoMap);

        // Test adding multiple entries
        crawlingInfoHelper.putToInfoMap("key2", "value2");
        crawlingInfoHelper.putToInfoMap("key3", "value3");

        assertEquals("value1", crawlingInfoHelper.infoMap.get("key1"));
        assertEquals("value2", crawlingInfoHelper.infoMap.get("key2"));