init endpoint is setting this value to zero on return
https://github.com/aerogear/mobile-security-service/blob/db0c216bd5b00687256835c01bf84737f4d4c5a0/pkg/web/apps/apps_service.go#L238

may be a reason for not setting it to omitonempty in the version model
https://github.com/aerogear/mobile-security-service/blob/db0c216bd5b00687256835c01bf84737f4d4c5a0/pkg/models/version.go#L12