[ORKNavigableOrderedTask] Return empty dictionaries instead of empty arrays
[ORKNavigableOrderedTask] Return empty dictionaries instead of empty arrays

YuanZhu-apple/ResearchKit,oliverschaefer/ResearchKit,md0u80c9/ResearchKit,weijentu/ResearchKit,oliverschaefer/ResearchKit,md0u80c9/ResearchKit,mluedke2/ResearchKit,mluedke2/ResearchKit,YuanZhu-apple/ResearchKit,cornelltech/ResearchKit,weijentu/ResearchKit,chb/ResearchKit,boland25/ResearchKit,boland25/ResearchKit,chb/ResearchKit,YuanZhu-apple/ResearchKit,jeremiahyan/ResearchKit,md0u80c9/ResearchKit,YuanZhu-apple/ResearchKit,oliverschaefer/ResearchKit,jeremiahyan/ResearchKit,boland25/ResearchKit,mluedke2/ResearchKit,jeremiahyan/ResearchKit,weijentu/ResearchKit,boland25/ResearchKit,chb/ResearchKit,md0u80c9/ResearchKit,chb/ResearchKit,oliverschaefer/ResearchKit,weijentu/ResearchKit,cornelltech/ResearchKit,cornelltech/ResearchKit