diff --git a/crates/extra/src/concurrency_limiter.rs b/crates/extra/src/concurrency_limiter.rs
index 8a2078adf..a663ae3d5 100644
--- a/crates/extra/src/concurrency_limiter.rs
+++ b/crates/extra/src/concurrency_limiter.rs
@@ -1,9 +1,9 @@
-//! size limiter middleware
+//! concurrency limiter middleware
 
 use tokio::sync::Semaphore;
 
 use salvo_core::http::StatusError;
-use salvo_core::http::{Body, Request, Response};
+use salvo_core::http::{Request, Response};
 use salvo_core::{async_trait, Depot, FlowCtrl, Handler};
 
 /// MaxConcurrency
diff --git a/crates/oapi/src/lib.rs b/crates/oapi/src/lib.rs
index 1de903a18..b1cd2d5b0 100644
--- a/crates/oapi/src/lib.rs
+++ b/crates/oapi/src/lib.rs
@@ -230,7 +230,7 @@ impl ToSchema for StatusError {
                 .property("name", String::to_schema(components))
                 .required("brief")
                 .property("brief", String::to_schema(components))
-                .required("brief")
+                .required("detail")
                 .property("detail", String::to_schema(components))
                 .property("cause", String::to_schema(components)),
         );
diff --git a/crates/oapi/src/openapi/schema/object.rs b/crates/oapi/src/openapi/schema/object.rs
index dcb55604d..558ca4089 100644
--- a/crates/oapi/src/openapi/schema/object.rs
+++ b/crates/oapi/src/openapi/schema/object.rs
@@ -1,5 +1,6 @@
 use std::collections::BTreeMap;
 
+use indexmap::IndexSet;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
@@ -50,8 +51,8 @@ pub struct Object {
     pub enum_values: Option<Vec<Value>>,
 
     /// Vector of required field names.
-    #[serde(skip_serializing_if = "Vec::is_empty", default = "Vec::new")]
-    pub required: Vec<String>,
+    #[serde(skip_serializing_if = "IndexSet::is_empty", default = "IndexSet::new")]
+    pub required: IndexSet<String>,
 
     /// Map of fields with their [`Schema`] types.
     ///
@@ -194,7 +195,7 @@ impl Object {
 
     /// Add field to the required fields of [`Object`].
     pub fn required(mut self, required_field: impl Into<String>) -> Self {
-        self.required.push(required_field.into());
+        self.required.insert(required_field.into());
         self
     }