Get value from form fields with service task (job worker)

Greetings everyone,
I hope someone can help me with this problem.
I’m trying to get the values ​​of the fields of a form in camunda through a service task, when I use a Camunda Form (embedded) the job worker can retrieve the values ​​of the form fields normally, but when I use a Camunda Form (linked) I receive the following error in the java service:

 Cannot invoke "Object.toString()" because the return value of "java.util.Map.get(Object)" is null

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