this sighting was certified a sleeper weed - certainly not sleeping east of the Fair where 3 different cultivars have been planted as Street trees and do their best to invade nature reserve ... I learnt today, that they invade residents tiny gardens and public space at the Fair and the rose garden which has a 1.5 m tall Callery pear iplanted by birds. This is already a nightmare and not a sleeper ... see also https://majura.org/callery-pear-request-to-stop-the-invasive-nightmare/
Another possibility is H. eriantha - see description at https://apps.lucidcentral.org/plants_se_nsw/text/entities/hakea_eriantha.htm where it says the nuts can be more or less smooth, and it is "Widely planted in Canberra. Naturalised in the ACT." We have it in our Flora list for Mt M and Mt A. Look at Hakea eriantha (Tree Hakea)
Hakea repullulans : Furze Hakea is the name given in ALA and VicFlora to the one Waltraud talks about above. See https://bie.ala.org.au/species/https://id.biodiversity.org.au/node/apni/2904740 and https://vicflora.rbg.vic.gov.au/flora/taxon/3380f985-a9aa-423d-a0c4-50d450e38cd6