public static String toPrintableString(byte bytes,
Converts an HTTP header line in byte form to a printable String.
Bytes corresponding to visible ASCII characters will converted to those
characters. All other bytes (0x00 to 0x1F, 0x7F to OxFF) will be
represented in 0xNN form.
bytes - Contains an HTTP header line
offset - The start position of the header line in the array
len - The length of the HTTP header line
A String with non-printing characters replaced by the 0xNN