[JENKINS-24719] Add capability of specifying no default value for manual builds

If I do not specify any default nodes when configuring the Node parameter, then when I manually run the job, the dropdown list is still populated with a default node (I believe this is the first node of the available node list after the "ALL" entry).

Would like the capability of truly specifying "no default" (e.g., default node would be "NO_DEFAULT" or "NONE"). For this default case, it would be expected that the user would be forced to select a valid node from the list of possible nodes. Otherwise, if they left the default, the job would immediately fail. Ideally some error message informing the user that they need to select a valid node would be output to the console log.

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Originally reported by sarchule, imported from: Add capability of specifying no default value for manual builds

• status: Open
  
• priority: Major
  
• component(s): nodelabelparameter-plugin
  
• resolution: Unresolved
  
• votes: 0
  
• watchers: 1
  
• imported: 20251210-235911
  

Raw content of original issue

If I do not specify any default nodes when configuring the Node parameter, then when I manually run the job, the dropdown list is still populated with a default node (I believe this is the first node of the available node list after the "ALL" entry). 


Would like the capability of truly specifying "no default" (e.g., default node would be "NO_DEFAULT" or "NONE"). For this default case, it would be expected that the user would be forced to select a valid node from the list of possible nodes. Otherwise, if they left the default, the job would immediately fail. Ideally some error message informing the user that they need to select a valid node would be output to the console log.

environment

```
Jenkins ver: 1.554.3

Plugin version: 1.5.1
```

No source file or test is named. Start by locating the nodelabelparameter-plugin Node parameter configuration and manual-build handling, then trace how an empty default is converted into the selected node. Done means a deliberate no-default option forces a valid node selection and reports an appropriate failure when none is chosen.

Written by the indexing model from the issue text.