public void putInt1_4BytesAs4(int number) {
        if (number < 0) {
            throw new IllegalArgumentException("Cannot encode negative number");
        }
        //no need to check upper boundary, since INT_MAX == 2^31
        putInt(number | 0x80000000);
    }
Writes a 31-bit positive integer to the buffer, using 4 bytes.

@param number the integer to write
vespajlib/src/main/java/com/yahoo/io/GrowableByteBuffer.java