I have never heard it called Adam's Laburnum before..... probably because I have never looked as it seems common enough now that I have.
As you will no doubt appreciate, it isn't a Laburnum, or at least only (around) half is - it is a graft chimera between Laburnum and Cytisus (broom).
Personally, I have never believed the catalogue or plant label photo's and about the only comment that I can find is that those are fantasy plants bred and propagated in Photoshop.
My go-to for short sharp accurate descriptions of garden plants - Kenneth A Beckett, Concise Encyclopedia.... - makes little comment implying that it should flower as per Laburnum. That said, +Laburnocytisus is very highly likely to be one clone whereas garden Laburnums are going to have been selected almost to death for all that gardeners look for.