public void putInt1_2_4BytesAs4(int number) {
        if (number < 0) {
            throw new IllegalArgumentException("Cannot encode negative number");
        } else if (number > 0x3FFFFFFF) {
            throw new IllegalArgumentException("Cannot encode number larger than 2^30.");
        }
        putInt(number | 0xC0000000);
    }
Writes a 30-bit positive integer to the buffer, using 4 bytes.

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