Searches of Mobile Phones and Visa Cancellation

When does an officer of the Australian Border Force have legal authority to search someone’s mobile phone in immigration clearance?
That question was presented in a case that was recently considered by Judge Dowdy of the Federal Circuit Court in a recent case, DOZ16 v Minister for Immigration (2017) FCCA 1157 (6 June 2017).
These were the circumstances of the case:
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