Try to use this, I’ve added parameters to remove "{} from key and values. But, it’s not perfect, because of Country contains json.
rule "key_value_parser"
when
has_field("Full_Response")
then
set_fields(
fields:
key_value(
value: to_string($message.Full_Response),
delimiters:",",
kv_delimiters:":",
trim_key_chars:"\"",
trim_value_chars: "\"{}")
);
end