Fixed bad forward merge of 7_0_X changes into DataMixingModule

The auto-merge of 7_0_X into 7_1_X put the DataMixingModule into a
bad state because of API changes between the two releases. This
commit should make the code work again in 7_1_X.
Merge pull request #3097 from Dr15Jones/emergencyBadMergeFixForDataMixingModule

Sim -- Fixed bad forward merge of 7_0_X changes into DataMixingModule