public static byte[] readVariableBytes(InputStream input, int width)
            throws SerializationException {
        int length = readNumber(input, width);
        return readFixedBytes(input, length);
    }
Read a length-prefixed sequence of bytes.
The length must be encoded in big endian format.
@param width the width of the length prefix, in bytes.
@throws SerializationException if EOF is encountered, or if {@code width} is negative or
greater than 4
common/src/main/java/org/conscrypt/ct/Serialization.java