PROC-123 - First: Remove the need to call generated code with an explicit fallback
PROC-123 - Second: Fix is*Fallback so that it returns 'true' when the fallback value is used
PROC-123 - Second: fix the group value accessors

- getEnumtst should be nonnull since we can always determine the fallback bucket
- isEnumtstFallback should be true when no assignment is made
PROC-123 - Make sure that payloads respect the fallback bucket as well
PROC-123 - new variant of getPayload is also @Nonnull
Merge branch 'jira/PROC-123/better-fallbacks' into 'master'

PROC-123: Generated proctor groups should respect fallback in boolean accessors