public void putInt2_4_8BytesAs4(long number) {
        if (number < 0L) {
            throw new IllegalArgumentException("Cannot encode negative number.");
        } else if (number > 0x7FFFFFFFL) {
            throw new IllegalArgumentException("Cannot encode number larger than 2^31-1.");
        }
        putInt(((int) number) | 0x80000000);
    }
Writes a 32 bit positive integer (or 31 bit unsigned) to the buffer,
using 4 bytes.

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