Custom sampler do not take constant in Raven code interface

[JiaZhou-PU]

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Issue Description

What did you expect to see happen?

When running RAVEN using the custom sampler, it should read constants

What did you see instead?

When generating inputs in RAVEN inputs, custom samplers do not read the constant.

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For Change Control Board: Issue Review

This review should occur before any development is performed as a response to this issue.

• 1. Is it tagged with a type: defect or task?
• 2. Is it tagged with a priority: critical, normal or minor?
• 3. If it will impact requirements or requirements tests, is it tagged with requirements?
• 4. If it is a defect, can it cause wrong results for users? If so an email needs to be sent to the users.
• 5. Is a rationale provided? (Such as explaining why the improvement is needed or why current code is wrong.)

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For Change Control Board: Issue Closure

This review should occur when the issue is imminently going to be closed.

• 1. If the issue is a defect, is the defect fixed?
• 2. If the issue is a defect, is the defect tested for in the regression test system? (If not explain why not.)
• 3. If the issue can impact users, has an email to the users group been written (the email should specify if the defect impacts stable or master)?
• 4. If the issue is a defect, does it impact the latest release branch? If yes, is there any issue tagged with release (create if needed)?
• 5. If the issue is being closed without a pull request, has an explanation of why it is being closed been provided?

[wangcj05]

@PaulTalbot-INL I think an email should send to the user when this issue is closed with PR #1120

[PaulTalbot-INL]

I think we try to reserve defect resolution announcements for behaviors that can result in incorrect results (see the issue review checklist above). I agree this fix can go in the next feature release announcement, though.