[24] As that judgment makes clear, the conclusion in Kell & Rigby, that the requirement for a notice under s 21(2) is mandatory, does not answer the present question, which is whether the adjudication is void where the adjudicator has decided, albeit wrongly, that there had been compliance with that provision. The judgment of Hodgson JA in Brodyn indicates that this requirement for a notice under s 21(2) is not an essential requirement, in the sense that it was an essential precondition of the existence of an adjudicator's determination. With regard to the purpose of this legislation, there is no reason why this requirement within s 21(2) should be an essential requirement although, for example, the time limit within s 21(3) should not be essential: cf Project Blue Sky Inc v Australian Broadcasting Authority.[11] Of course s 21(2) provides that an adjudication application "can not be made" unless there is such a notice and these precise words are not replicated in s 21(3). Nevertheless, s 21(3) provides that an adjudication application "must be made" within the times there set out. In each case the words are "emphatic",[12] and in my view there is no basis for distinguishing between the two provisions on the basis of this difference in words.