Update FilterMixin to inspect the serializer fields that exist after the serializer has been initialized instead of only fields that are declared ahead of time.
Update FilterMixin to inspect the serializer fields that exist after the serializer has been initialized instead of only fields that are declared ahead of time.

Johnetordoff/osf.io,Johnetordoff/osf.io,felliott/osf.io,adlius/osf.io,mattclark/osf.io,adlius/osf.io,CenterForOpenScience/osf.io,cslzchen/osf.io,Johnetordoff/osf.io,CenterForOpenScience/osf.io,felliott/osf.io,felliott/osf.io,brianjgeiger/osf.io,mfraezz/osf.io,adlius/osf.io,cslzchen/osf.io,CenterForOpenScience/osf.io,mfraezz/osf.io,saradbowman/osf.io,aaxelb/osf.io,cslzchen/osf.io,mfraezz/osf.io,mattclark/osf.io,aaxelb/osf.io,aaxelb/osf.io,brianjgeiger/osf.io,baylee-d/osf.io,felliott/osf.io,aaxelb/osf.io,cslzchen/osf.io,saradbowman/osf.io,mattclark/osf.io,brianjgeiger/osf.io,baylee-d/osf.io,Johnetordoff/osf.io,brianjgeiger/osf.io,adlius/osf.io,mfraezz/osf.io,baylee-d/osf.io,CenterForOpenScience/osf.io