Output os = ByteString.newOutput(5);
os.write(new byte[] {1, 2, 3, 4, 5});
EvilOutputStream eos = new EvilOutputStream();
os.writeTo(eos);
byte[] capturedArray = eos.capturedArray;
ByteString byteString = os.toByteString();
byte[] oldValue = byteString.toByteArray();
Arrays.fill(capturedArray, (byte) 0);
byte[] newValue = byteString.toByteArray();
assertTrue("Output must not provide access to the underlying byte array",
Arrays.equals(oldValue, newValue));