redo detect content type on respond

go.mod

@@ -12,3 +12,10 @@ require (
 	golang.org/x/sys v0.0.0-20210923061019-b8560ed6a9b7 // indirect
 	gopkg.in/go-playground/assert.v1 v1.2.1 // indirect
 )
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-playground/locales v0.14.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+)

responder.go

@@ -18,6 +18,7 @@ func RespondJSON(w http.ResponseWriter, r *http.Request, code int, data interfac
 		})
 		return Respond(w, r, http.StatusInternalServerError, resp)
 	}
+	w.Header().Set("Content-Type", "application/json")
 	return Respond(w, r, code, jsonData)
 }
 
@@ -31,8 +32,12 @@ func Respond(w http.ResponseWriter, r *http.Request, code int, data []byte) (int
 	if err != nil {
 		return -1, err
 	}
-	contentType := http.DetectContentType(data)
-	w.Header().Set("Content-Type", contentType)
+
+	// content type is not set so attempt to set it
+	if w.Header().Get("Content-Type") == "" {
+		w.Header().Set("Content-Type", http.DetectContentType(data))
+	}
+
 	w.WriteHeader(code)
 	return w.Write(data)
 }