public Charset getCharset() {
            return charset;
        }
@return A {@link DecodedChar} representing the character decoded from n bytes supplied by byteSupplier or
null if byteSupplier has no bytes to supply.
@throws DecoderException If it fails to decode a char after consuming MAX_BYTES_PER_CHAR bytes
                         from byteSupplier
stroom-pipeline/src/main/java/stroom/pipeline/reader/ByteStreamDecoder.java