Getting java.util.regex.PatternSyntaxException: Illegal repetition whenever I am trying to pass nested json string in my request header

I am using open feign to communicate to rest endpoints from a spring boot application.
In the feign client declaration I am using spring web annotation such as @RequestHeader and @GetMapping. Now in the param which is annotated with @RequestHeader, if i pass one level json String like {"attr1": "value1" , "attr2" : "value2"} the rest calls flows to the target application. But if I pass any nested json like {"attr1": {"attr2" : "value2"}} , the code fails with the below error

Getting java.util.regex.PatternSyntaxException: Illegal repetition.

Start with the Feign client declaration and the @RequestHeader parameter handling described in the issue, then reproduce the request with a nested JSON string. Done means the nested value no longer causes PatternSyntaxException and the REST call reaches the target application.