rename method and update comment

Author: joeyzhao2018

bottlecap/src/lifecycle/invocation/triggers/msk_event.rs

@@ -55,9 +55,10 @@ fn bytes_from_header_value(val: &Value) -> Option<Vec<u8>> {
     }
 }
 
-/// Extracts trace propagation headers from an MSK record's `headers` field into a carrier map.
-/// The `headers` field is a JSON object with numeric string keys, one entry per Kafka header.
-fn carrier_from_headers(headers: &Value) -> HashMap<String, String> {
+/// Decodes an MSK record's `headers` field into a `HashMap<String, String>` by converting
+/// each header's byte values to a UTF-8 string. The `headers` field may be either a JSON 
+/// array or a JSON object with numeric string keys, one entry per Kafka header, ordered by index.
+fn headers_to_string_map(headers: &Value) -> HashMap<String, String> {
     let mut carrier = HashMap::new();
 
     let entries: Vec<&Value> = match headers {
@@ -185,7 +186,7 @@ impl Trigger for MSKEvent {
         self.records
             .values()
             .find_map(|arr| arr.first())
-            .map_or_else(HashMap::new, |record| carrier_from_headers(&record.headers))
+            .map_or_else(HashMap::new, |record| headers_to_string_map(&record.headers))
     }
 
     fn is_async(&self) -> bool {