int nextByte(CharsetDetector det) {
            if (nextIndex >= det.fRawLength) {
                done = true;
                return -1;
            }
            return (int) det.fRawInput[nextIndex++] & 0x00ff;
        }
Get the next character (however many bytes it is) from the input data
Subclasses for specific charset encodings must implement this function
to get characters according to the rules of their encoding scheme.
<p>
This function is not a method of class iteratedChar only because
that would require a lot of extra derived classes, which is awkward.

@param it  The iteratedChar "struct" into which the returned char is placed.
@param det The charset detector, which is needed to get at the input byte data
           being iterated over.
@return True if a character was returned, false at end of input.
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-text-module/src/main/java/org/apache/tika/parser/txt/CharsetRecog_mbcs.java