fix: refactor syntax to correctly include structs (#1580)

This PR fixes a compilation bug related to conditionally adding docs
behind a feature flag

router/src/server.rs

@@ -1037,7 +1037,12 @@ pub async fn run(
     };
 
     // Define VertextApiDoc conditionally only if the "google" feature is enabled
+    let doc = {
+        // avoid `mut` if possible
         #[cfg(feature = "google")]
+        {
+            use crate::VertexInstance;
+
             #[derive(OpenApi)]
             #[openapi(
                 paths(vertex_compatibility),
@@ -1045,12 +1050,8 @@ pub async fn run(
             )]
             struct VertextApiDoc;
 
-    let doc = {
-        // avoid `mut` if possible
-        #[cfg(feature = "google")]
-        {
             // limiting mutability to the smallest scope necessary
-            let mut doc = doc;
+            let mut doc = ApiDoc::openapi();
             doc.merge(VertextApiDoc::openapi());
             doc
         }