Clear the value of "Parent Link" field when creating a new issue

[Abhishek Kalamkar]

When creating a new issue, I need to clear the parent field. Parent link should be empty. 

I have tried multiple options like 

{
    "fields": {
        "parent": null  
    }
}

and 

{
"update" : {
"Parent Link" : [{"set": []}]
}
}

does not seems to work. 

can you please help to sort the issue out. 

[Roberto Marquez Bittencourt]

Hi, i did more tests and it seems to me that the error is caused by the condition of the transition and not by the validator. I use the following condition:

Simple scripted condition (condition apply).

(cfValues['Data de Início Planejada'] == null) || (cfValues['Data de Fim Planejada'] == null)

This way, the transition should appear if one of the two date fields is not filled. And when I test in the new environment Jira 7.9.2 and Script Runner 5.4.12, no error occurs, but in the production environment Jira 6.3.1 and Script Runner 3.1.4, the error occurs.