Use with_body instead of with_body_text_plain for JSON responses

The with_body_text_plain method sets Content-Type to text/plain,
overriding the APPLICATION_JSON type set by with_content_type.
Replace all 6 occurrences in request signing endpoints with
with_body which preserves the previously set Content-Type.

Closes #424

Author: ChristianPavilonis

crates/trusted-server-core/src/request_signing/endpoints.rs

@@ -48,7 +48,7 @@ pub fn handle_trusted_server_discovery(
 
     Ok(Response::from_status(200)
         .with_content_type(fastly::mime::APPLICATION_JSON)
-        .with_body_text_plain(&json))
+        .with_body(json))
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -118,7 +118,7 @@ pub fn handle_verify_signature(
 
     Ok(Response::from_status(200)
         .with_content_type(fastly::mime::APPLICATION_JSON)
-        .with_body_text_plain(&response_json))
+        .with_body(response_json))
 }
 
 #[derive(Debug, Deserialize, Serialize)]
@@ -199,7 +199,7 @@ pub fn handle_rotate_key(
 
             Ok(Response::from_status(200)
                 .with_content_type(fastly::mime::APPLICATION_JSON)
-                .with_body_text_plain(&response_json))
+                .with_body(response_json))
         }
         Err(e) => {
             let response = RotateKeyResponse {
@@ -220,7 +220,7 @@ pub fn handle_rotate_key(
 
             Ok(Response::from_status(500)
                 .with_content_type(fastly::mime::APPLICATION_JSON)
-                .with_body_text_plain(&response_json))
+                .with_body(response_json))
         }
     }
 }
@@ -305,7 +305,7 @@ pub fn handle_deactivate_key(
 
             Ok(Response::from_status(200)
                 .with_content_type(fastly::mime::APPLICATION_JSON)
-                .with_body_text_plain(&response_json))
+                .with_body(response_json))
         }
         Err(e) => {
             let response = DeactivateKeyResponse {
@@ -329,7 +329,7 @@ pub fn handle_deactivate_key(
 
             Ok(Response::from_status(500)
                 .with_content_type(fastly::mime::APPLICATION_JSON)
-                .with_body_text_plain(&response_json))
+                .with_body(response_json))
         }
     }
 }