fix: prevent logging of header values in tonic debug logs (#3465)

Author: rornic

opentelemetry-otlp/CHANGELOG.md

@@ -51,6 +51,7 @@
 - Fixed [#2777](https://github.com/open-telemetry/opentelemetry rust/issues/2777)  to properly handle `shutdown_with_timeout()` when using `grpc-tonic`.
 - Deprecate `tls` feature in favor of explicit `tls-ring` and `tls-aws-lc` features.
   **Migration**: Replace `tls` with `tls-ring` (or `tls-aws-lc`). Users of `tls-roots` or `tls-webpki-roots` must now also enable one of these.
+- Prevent logging of header values in OTLP tonic exporter [#3465](https://github.com/open-telemetry/opentelemetry-rust/pull/3465)
 
 ## 0.31.0
 

opentelemetry-otlp/src/exporter/tonic/mod.rs

@@ -232,6 +232,7 @@ impl TonicExporterBuilder {
         let compression = self.resolve_compression(signal_compression_var)?;
 
         let (headers_from_env, headers_for_logging) = parse_headers_from_env(signal_headers_var);
+
         let metadata = merge_metadata_with_headers_from_env(
             self.tonic_config.metadata.unwrap_or_default(),
             headers_from_env,
@@ -586,7 +587,7 @@ fn merge_metadata_with_headers_from_env(
     }
 }
 
-fn parse_headers_from_env(signal_headers_var: &str) -> (HeaderMap, Vec<(String, String)>) {
+fn parse_headers_from_env(signal_headers_var: &str) -> (HeaderMap, Vec<String>) {
     let mut headers = Vec::new();
 
     (
@@ -595,7 +596,7 @@ fn parse_headers_from_env(signal_headers_var: &str) -> (HeaderMap, Vec<(String,
             .map(|input| {
                 parse_header_string(&input)
                     .filter_map(|(key, value)| {
-                        headers.push((key.to_owned(), value.clone()));
+                        headers.push(key.to_owned());
                         Some((
                             HeaderName::from_str(key).ok()?,
                             HeaderValue::from_str(&value).ok()?,