diff --git a/bin/configs/go-multiple-allof-ref-with-discriminator.yaml b/bin/configs/go-multiple-allof-ref-with-discriminator.yaml
index c2c8a195dc56..6fba9b41b1fa 100644
--- a/bin/configs/go-multiple-allof-ref-with-discriminator.yaml
+++ b/bin/configs/go-multiple-allof-ref-with-discriminator.yaml
@@ -1,5 +1,6 @@
 generatorName: go
 outputDir: samples/client/others/go/allof_multiple_ref_and_discriminator
 inputSpec: modules/openapi-generator/src/test/resources/3_0/go/allof_multiple_ref_and_discriminator.yaml
+templateDir: modules/openapi-generator/src/main/resources/go
 additionalProperties:
   hideGenerationTimestamp: "true"
diff --git a/bin/configs/go-oneof-anyof-required.yaml b/bin/configs/go-oneof-anyof-required.yaml
index c91e0baa4a32..172b4cfd9892 100644
--- a/bin/configs/go-oneof-anyof-required.yaml
+++ b/bin/configs/go-oneof-anyof-required.yaml
@@ -1,5 +1,6 @@
 generatorName: go
 outputDir: samples/client/others/go/oneof-anyof-required
 inputSpec: modules/openapi-generator/src/test/resources/3_0/go/spec-with-oneof-anyof-required.yaml
+templateDir: modules/openapi-generator/src/main/resources/go
 additionalProperties:
   hideGenerationTimestamp: "true"
diff --git a/bin/configs/go-oneof-discriminator-lookup.yaml b/bin/configs/go-oneof-discriminator-lookup.yaml
index b6b9e7ad28ef..1e1beb632355 100644
--- a/bin/configs/go-oneof-discriminator-lookup.yaml
+++ b/bin/configs/go-oneof-discriminator-lookup.yaml
@@ -1,6 +1,7 @@
 generatorName: go
 outputDir: samples/client/others/go/oneof-discriminator-lookup
 inputSpec: modules/openapi-generator/src/test/resources/3_0/go/spec-with-oneof-discriminator.yaml
+templateDir: modules/openapi-generator/src/main/resources/go
 additionalProperties:
   useOneOfDiscriminatorLookup: "true"
   hideGenerationTimestamp: "true"
diff --git a/modules/openapi-generator/src/main/resources/go/client.mustache b/modules/openapi-generator/src/main/resources/go/client.mustache
index dea298410dc3..9c189b8dc212 100644
--- a/modules/openapi-generator/src/main/resources/go/client.mustache
+++ b/modules/openapi-generator/src/main/resources/go/client.mustache
@@ -592,10 +592,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/client/echo_api/go-external-refs/client.go b/samples/client/echo_api/go-external-refs/client.go
index 0acd53304c6a..01f4055c6cfe 100644
--- a/samples/client/echo_api/go-external-refs/client.go
+++ b/samples/client/echo_api/go-external-refs/client.go
@@ -513,10 +513,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/client/echo_api/go/client.go b/samples/client/echo_api/go/client.go
index 0acd53304c6a..01f4055c6cfe 100644
--- a/samples/client/echo_api/go/client.go
+++ b/samples/client/echo_api/go/client.go
@@ -513,10 +513,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/client/others/go/allof_multiple_ref_and_discriminator/client.go b/samples/client/others/go/allof_multiple_ref_and_discriminator/client.go
index 6fce88a8015a..f797d2c4d2b3 100644
--- a/samples/client/others/go/allof_multiple_ref_and_discriminator/client.go
+++ b/samples/client/others/go/allof_multiple_ref_and_discriminator/client.go
@@ -484,10 +484,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/client/others/go/oneof-anyof-required/client.go b/samples/client/others/go/oneof-anyof-required/client.go
index 6fce88a8015a..f797d2c4d2b3 100644
--- a/samples/client/others/go/oneof-anyof-required/client.go
+++ b/samples/client/others/go/oneof-anyof-required/client.go
@@ -484,10 +484,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/client/others/go/oneof-discriminator-lookup/client.go b/samples/client/others/go/oneof-discriminator-lookup/client.go
index 6fce88a8015a..f797d2c4d2b3 100644
--- a/samples/client/others/go/oneof-discriminator-lookup/client.go
+++ b/samples/client/others/go/oneof-discriminator-lookup/client.go
@@ -484,10 +484,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/client/petstore/go/go-petstore/client.go b/samples/client/petstore/go/go-petstore/client.go
index c47d065a79aa..82ace87a5306 100644
--- a/samples/client/petstore/go/go-petstore/client.go
+++ b/samples/client/petstore/go/go-petstore/client.go
@@ -519,10 +519,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/client.go b/samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/client.go
index ef706c87728c..9b0df1df106f 100644
--- a/samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/client.go
+++ b/samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/client.go
@@ -487,10 +487,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/openapi3/client/petstore/go-petstore-generateMarshalJSON-false/client.go b/samples/openapi3/client/petstore/go-petstore-generateMarshalJSON-false/client.go
index 9560cb90583f..2747d3b9714f 100644
--- a/samples/openapi3/client/petstore/go-petstore-generateMarshalJSON-false/client.go
+++ b/samples/openapi3/client/petstore/go-petstore-generateMarshalJSON-false/client.go
@@ -499,10 +499,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/openapi3/client/petstore/go-petstore-withXml/client.go b/samples/openapi3/client/petstore/go-petstore-withXml/client.go
index 9560cb90583f..2747d3b9714f 100644
--- a/samples/openapi3/client/petstore/go-petstore-withXml/client.go
+++ b/samples/openapi3/client/petstore/go-petstore-withXml/client.go
@@ -499,10 +499,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore-aws-signature/client.go b/samples/openapi3/client/petstore/go/go-petstore-aws-signature/client.go
index 7d9664e41128..79d1274dfd0c 100644
--- a/samples/openapi3/client/petstore/go/go-petstore-aws-signature/client.go
+++ b/samples/openapi3/client/petstore/go/go-petstore-aws-signature/client.go
@@ -541,10 +541,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {
diff --git a/samples/openapi3/client/petstore/go/go-petstore/client.go b/samples/openapi3/client/petstore/go/go-petstore/client.go
index 3f017c316e8e..259fda811873 100644
--- a/samples/openapi3/client/petstore/go/go-petstore/client.go
+++ b/samples/openapi3/client/petstore/go/go-petstore/client.go
@@ -537,10 +537,7 @@ func addFile(w *multipart.Writer, fieldName, path string) error {
 	if err != nil {
 		return err
 	}
-	err = file.Close()
-	if err != nil {
-		return err
-	}
+	defer file.Close()
 
 	part, err := w.CreateFormFile(fieldName, filepath.Base(path))
 	if err != nil {