[Go] Fix operation files clobbering model files. [2.4.0] (#7337)

* Prevent operation files clobbering model files.

* Update Tests

samples/server/petstore/go-api-server/go/api_pet.go

@@ -0,0 +1,55 @@
+/*
+ * Swagger Petstore
+ *
+ * This is a sample server Petstore server.  You can find out more about Swagger at [http://swagger.io](http://swagger.io) or on [irc.freenode.net, #swagger](http://swagger.io/irc/).  For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * API version: 1.0.0
+ * Contact: apiteam@swagger.io
+ * Generated by: Swagger Codegen (https://github.com/swagger-api/swagger-codegen.git)
+ */
+
+package petstoreserver
+
+import (
+	"net/http"
+)
+
+func AddPet(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func DeletePet(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func FindPetsByStatus(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func FindPetsByTags(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func GetPetById(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func UpdatePet(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func UpdatePetWithForm(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}
+
+func UploadFile(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json; charset=UTF-8")
+	w.WriteHeader(http.StatusOK)
+}