Update handling of user attributes in MPUploadBuilder
Update handling of user attributes in MPUploadBuilder

mParticle/mparticle-apple-sdk,mParticle/mparticle-apple-sdk,mParticle/mparticle-apple-sdk,mParticle/mparticle-apple-sdk,mParticle/mparticle-apple-sdk,mParticle/mParticle-iOS-SDK,mParticle/mParticle-iOS-SDK,mParticle/mParticle-iOS-SDK,mParticle/mparticle-apple-sdk