fix(logger): ensure custom key formats are kept when cleared

Author: eliasbrange

aws_lambda_powertools/logging/formatter.py

@@ -127,8 +127,8 @@ def __init__(
 
         super(LambdaPowertoolsFormatter, self).__init__(datefmt=self.datefmt)
 
-        keys_combined = {**self._build_default_keys(), **kwargs}
-        self.log_format.update(**keys_combined)
+        self.keys_combined = {**self._build_default_keys(), **kwargs}
+        self.log_format.update(**self.keys_combined)
 
     def serialize(self, log: Dict) -> str:
         """Serialize structured log dict to JSON str"""
@@ -187,7 +187,7 @@ def remove_keys(self, keys: Iterable[str]):
 
     def clear_state(self):
         self.log_format = dict.fromkeys(self.log_record_order)
-        self.log_format.update(**self._build_default_keys())
+        self.log_format.update(**self.keys_combined)
 
     @staticmethod
     def _build_default_keys():