Reads bytes from {@link InputStream} and constructs a {@link Message}.
The design encourages lazy decoding of a {@link Message}, where a {@link Message} is returned even before the whole message is parsed,and additional parsing is done as the {@link Message} body is read along.A {@link Codec} is most likely have its own implementation of {@link Message}for this purpose.
@param in the data to be read into a {@link Message}. The transport would have read any transport-specific header before it passes an {@link InputStream}, and {@link InputStream} is expected to be read until EOS. Never null.
Some transports, such as SMTP, may 'encode' data into another format (such as uuencode, base64, etc.) It is the caller's responsibility to 'decode' these transport-level encoding before it passes data into {@link Codec}.
@param contentType The MIME content type (like "application/xml") of this byte stream. Thie text includes all the sub-headers of the content-type header. Therefore, in more complex case, this could be something like multipart/related; boundary="--=_outer_boundary"; type="multipart/alternative". This parameter must not be null.
@param response The parsed {@link Message} will be set to this {@link Packet}. {@link Codec} may add additional properties to this {@link Packet}. On a successful method completion, a {@link Packet} must contain a{@link Message}.
@throws IOException if {@link InputStream} throws an exception.