String[] array = new String[elements.length];
    int i = 0;
    for (Object e : elements) {
      array[i++] = (String) e;
    }
    return create(array);
  }

  protected abstract Collection<String> create(String[] elements);

  @Override
  public String[] createArray(int length) {
    return new String[length];
  }

  /** Returns the original element list, unchanged. */

    String[] array = new String[elements.length];
    int i = 0;
    for (Object e : elements) {
      array[i++] = (String) e;
    }
    return create(array);
  }

  protected abstract Queue<String> create(String[] elements);

  @Override
  public String[] createArray(int length) {
    return new String[length];
  }

  /** Returns the original element list, unchanged. */
  @Override

    public void transferProgress(TransferEvent transferEvent, byte[] buffer, int length) {
        Long transferred;
        synchronized (transfers) {
            transferred = transfers.get(transferEvent.getResource());
            if (transferred == null) {
                transferred = (long) length;
            } else {
                transferred = transferred + length;
            }

        byte[] actualDescrBytes = new byte[expectedDescrBytes.length];
        System.arraycopy(dst, 2, actualDescrBytes, 0, expectedDescrBytes.length);
        assertArrayEquals(expectedDescrBytes, actualDescrBytes);

        // Verify level (0x0001 - 2 bytes)
        int descrEnd = 2 + expectedDescrBytes.length;
        assertEquals(0x01, dst[descrEnd]);
        assertEquals(0x00, dst[descrEnd + 1]);

    private final long sourceOffset;
    private final long targetOffset;
    private final int length;

    /**
     * Constructs a server copy chunk descriptor
     * @param soff the source file offset
     * @param toff the target file offset
     * @param len the length of data to copy
     */
    public SrvCopychunk(final long soff, final long toff, final int len) {
        this.sourceOffset = soff;

      return seq.toString();
    }

    @Override
    public boolean isEmpty() {
      return seq.length() == 0;
    }

    @Override
    public long length() {
      return seq.length();
    }

    @Override
    public Optional<Long> lengthIfKnown() {
      return Optional.of((long) seq.length());
    }

    /**

      return seq.toString();
    }

    @Override
    public boolean isEmpty() {
      return seq.length() == 0;
    }

    @Override
    public long length() {
      return seq.length();
    }

    @Override
    public Optional<Long> lengthIfKnown() {
      return Optional.of((long) seq.length());
    }

    /**

        assertEquals(7, WitnessEventType.NODE_AVAILABLE.getValue());

        // Verify all values are unique
        for (int i = 0; i < events.length; i++) {
            for (int j = i + 1; j < events.length; j++) {
                assertNotEquals(events[i].getValue(), events[j].getValue(),
                        "Event types " + events[i] + " and " + events[j] + " have the same value");
            }

        byte[] expected = new byte[1 + dirName.length() + 1];
        expected[0] = 0x04; // buffer format
        System.arraycopy(dirName.getBytes(), 0, expected, 1, dirName.length());
        expected[dirName.length() + 1] = 0x00; // null terminator

        byte[] dst = new byte[100];
        int len = sdd.writeBytesWireFormat(dst, 0);

        assertEquals(expected.length, len);

        byte[] result = new byte[len];

        }

        private String appendPath(String parentUrl, String childPath, String pathAdjustment) {
            StringBuilder url = new StringBuilder(parentUrl.length()
                    + pathAdjustment.length()
                    + childPath.length()
                    + ((pathAdjustment.isEmpty()) ? 1 : 2));

            url.append(parentUrl);
            concatPath(url, pathAdjustment);