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In large instances due to better performance please refer to functions bellow that described below as they allow to search within secure fields in narrowed limited range of issues.

Secure Field Search with JQL

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1 - Any JQL - like project = test, type issuetype = Task etc...
Please keep in mind that if your JQL contains any double quotation marks " please escape them - change to \" - or change to single quotation marks '. 
Fore example for JQL like project = "testSome Project" change it to project = \"testSome Project\"  or better change to project = 'test'.

2 - custom field's name

3 - operator's name

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