* @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
   */
  public static <T> T firstNonNull(@Nullable T first, @Nullable T second) {
    if (first != null) {
      return first;
    }
    if (second != null) {
      return second;
    }
    throw new NullPointerException("Both parameters are null");
  }

  /**
   * Creates an instance of {@link ToStringHelper}.
   *

        int result = smbComRename.writeBytesWireFormat(dst, dstIndex);

        // Then
        assertTrue(result > 0);
        assertEquals((byte) 0x04, dst[0]); // First buffer format byte

        // Find the second buffer format byte
        int secondBufferFormatIndex = oldFileName.length() + 2; // 1 for first 0x04, 1 for null terminator
        assertEquals((byte) 0x04, dst[secondBufferFormatIndex]);
    }

    /**

        assertThrows(IllegalStateException.class, () -> {
            Handler.setURLStreamHandlerFactory(mockFactory2); // Second call, should fail.
        }, "Setting the factory a second time should throw IllegalStateException.");
    }

    @Test
    void testOpenConnection_WithCustomFactory() throws Exception {

		lookupHost = net.DefaultResolver.LookupHost
	}

	if baseDialCtx == nil {
		// This is same as which `http.DefaultTransport` uses.
		baseDialCtx = (&net.Dialer{
			Timeout:   30 * time.Second,
			KeepAlive: 30 * time.Second,
		}).DialContext
	}

	return func(ctx context.Context, network, addr string) (conn net.Conn, err error) {
		host, port, err := net.SplitHostPort(addr)
		if err != nil {
			return nil, err
		}

    entry = cacheEntry1;
    if (entry != null && entry.key == key) {
      return entry.value;
    }
    entry = cacheEntry2;
    if (entry != null && entry.key == key) {
      // Promote second cache entry to first so the access pattern
      // [K1, K2, K1, K3, K1, K4...] still hits the cache half the time.
      addToCache(entry);
      return entry.value;
    }
    return null;
  }

  @Override

	if len(record) != size {
		size = len(record)
		record = strconv.Itoa(size) + " " + k + "=" + v + "\n"
	}
	return record, nil
}

// validPAXRecord reports whether the key-value pair is valid where each
// record is formatted as:
//
//	"%d %s=%s\n" % (size, key, value)
//
// Keys and values should be UTF-8, but the number of bad writers out there

  @CanIgnoreReturnValue
  public final <A extends Appendable> A appendTo(
      A appendable, @Nullable Object first, @Nullable Object second, @Nullable Object... rest)
      throws IOException {
    return appendTo(appendable, iterable(first, second, rest));
  }

  /**
   * Appends the string representation of each of {@code parts}, using the previously configured

 *   protected void visitWildcardType(WildcardType t) {
 *     throw new IllegalArgumentException("Cannot contain wildcard type.");
 *   }
 * }.visit(type);
 * }
 *
 * <p>One {@code Type} is visited at most once. The second time the same type is visited, it's
 * ignored by {@link #visit}. This avoids infinite recursion caused by recursive type bounds.
 *
 * <p>This class is not thread safe.
 *
 * @author Ben Yu
 */

func (initialSnapShot LeakDetect) DetectLeak(t TestErrHandler) {
	if t.Failed() {
		return
	}
	// Loop, waiting for goroutines to shut down.
	// Wait up to 5 seconds, but finish as quickly as possible.
	deadline := UTCNow().Add(leakDetectDeadline * time.Second)
	for {
		// get sack snapshot of relevant go routines.
		leaked := initialSnapShot.CompareCurrentSnapshot()
		// current stack snapshot matches the initial one, no leaks, return.

    }

    @Test
    @DisplayName("Iterator with rejecting filter - finds next acceptable")
    void iteratorWithRejectingFilter() throws Exception {
        // Setup: first entry rejected, second accepted
        FileEntry entry1 = mock(FileEntry.class);
        FileEntry entry2 = mock(FileEntry.class);

        when(delegate.hasNext()).thenReturn(true, true, false);