fix: use collect() instead of for loop

opentelemetry-otlp/tests/grpc_build.rs

@@ -40,17 +40,17 @@ fn build_grpc() {
 }
 
 fn build_content_map() -> HashMap<PathBuf, String> {
-    let mut map = HashMap::new();
-    let dict =
-        std::fs::read_dir("src/proto/grpcio").expect("cannot open dict of generated grpc files");
-
-    for entry in dict.into_iter().flatten() {
-        map.insert(
-            entry.path(),
-            std::fs::read_to_string(entry.path()).unwrap_or_else(|_| {
-                panic!("cannot read from file {}", entry.path().to_string_lossy())
-            }),
-        );
-    }
-    map
+    std::fs::read_dir("src/proto/grpcio")
+        .expect("cannot open dict of generated grpc files")
+        .into_iter()
+        .flatten()
+        .map(|entry| {
+            (
+                entry.path(),
+                std::fs::read_to_string(entry.path()).unwrap_or_else(|_| {
+                    panic!("cannot read from file {}", entry.path().to_string_lossy())
+                }),
+            )
+        })
+        .collect()
 }