public String decompress(String compressorName, String compressedString) throws IOException {
    Checks.notNull(compressedString, "compressedString cannot be null");
    Compressor compressor = getCompressor(compressorName);
    return new String(compressor.decompress(base64Decode(compressedString)), DEFAULT_ENCODING);
  }
@Test
  public void decompressShouldThrowExceptionIfCompressedStringIsNull() {
    AssertHelper.assertThrows(
        "decompress should throw exception if compressedString is null",
        NullPointerException.class,
        "compressedString cannot be null",
        () -> stringCodec.decompress("abcd", null));
  }