setting default value of DFF using Groovy script

Summary:

I want to default a DFF field using the Groovy which will call the get method of a rest API webservices . The Webservices reference is created in application composer and I am refering to that in the Groovy expression block .Have any one done this earlier

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Code Snippet (add any code snippets that support your topic, if applicable):

Code to call the webservices through Groovy Script:

adf.webServices.YourServiceVariableName.MethodName(args)