### Question:
BERTLVPackager extends GenericPackager { @Override public byte[] pack(ISOComponent m) throws ISOException { return pack(m, false, getFirstField(), m.getMaxField()); } BERTLVPackager(); @Override byte[] pack(ISOComponent m); byte[] pack(ISOComponent m, boolean nested, int startIdx, int endIdx); @Override int unpack(ISOComponent m, byte[] b); int unpack(ISOComponent m, byte[] b, boolean nested); @Override void unpack(ISOComponent m, InputStream in);  }### Answer:
@Test public void testZeroLength() throws ISOException { BERTLVPackager p = new BERTLVAsciiHexPackager(); ISOTaggedField t = new ISOTaggedField( EMVStandardTagType.APPLICATION_FILE_LOCATOR_0x94.getTagNumberHex(), new ISOField(0, "")); t.setFieldNumber(1); ISOMsg m = new ISOMsg(55); m.set(t); byte[] b = p.pack(m, true, 1, 1); assertArrayEquals(ISOUtil.hex2byte("39343030"), b, ISOUtil.hexString(b)); }