How to validate issuekey provided in linked issue field is bug type while duplicate transition

[Dayanand]

Hi all,

We have transition called duplicate when use clicks it window opens with field Linked Issue then  user choose as duplicate value then we will have another field call Issue (issue searchable field ) for this field how we write validator or scriptrunner script to validate that enter key is bug type then only transition otherwise through error massage (refer attached screenshot for more)