[Go-client] Fix inability to download files (#9812)

* Revert a change to the Go Client code that broke
the ability to download files. This reverts the change
from 14d41310b9

* Missed import for "io/ioutil"

* update samples

Co-authored-by: icubbon <icubbon@gmail.com>

modules/openapi-generator/src/main/resources/go/client.mustache

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"mime/multipart"
 	"net/http"
@@ -419,6 +420,15 @@ func (c *APIClient) decode(v interface{}, b []byte, contentType string) (err err
 		*s = string(b)
 		return nil
 	}
+	if f, ok := v.(**os.File); ok {
+		*f, err = ioutil.TempFile("", "HttpClientFile")
+		if err != nil {
+			return
+		}
+		_, err = (*f).Write(b)
+		_, err = (*f).Seek(0, io.SeekStart)
+		return
+	}
 	if xmlCheck.MatchString(contentType) {
 		if err = xml.Unmarshal(b, v); err != nil {
 			return err

samples/client/petstore/go/go-petstore/client.go

@@ -18,6 +18,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"mime/multipart"
 	"net/http"
@@ -374,6 +375,15 @@ func (c *APIClient) decode(v interface{}, b []byte, contentType string) (err err
 		*s = string(b)
 		return nil
 	}
+	if f, ok := v.(**os.File); ok {
+		*f, err = ioutil.TempFile("", "HttpClientFile")
+		if err != nil {
+			return
+		}
+		_, err = (*f).Write(b)
+		_, err = (*f).Seek(0, io.SeekStart)
+		return
+	}
 	if xmlCheck.MatchString(contentType) {
 		if err = xml.Unmarshal(b, v); err != nil {
 			return err

samples/openapi3/client/extensions/x-auth-id-alias/go-experimental/client.go

@@ -18,6 +18,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"mime/multipart"
 	"net/http"
@@ -359,6 +360,15 @@ func (c *APIClient) decode(v interface{}, b []byte, contentType string) (err err
 		*s = string(b)
 		return nil
 	}
+	if f, ok := v.(**os.File); ok {
+		*f, err = ioutil.TempFile("", "HttpClientFile")
+		if err != nil {
+			return
+		}
+		_, err = (*f).Write(b)
+		_, err = (*f).Seek(0, io.SeekStart)
+		return
+	}
 	if xmlCheck.MatchString(contentType) {
 		if err = xml.Unmarshal(b, v); err != nil {
 			return err

samples/openapi3/client/petstore/go/go-petstore/client.go

@@ -18,6 +18,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"mime/multipart"
 	"net/http"
@@ -387,6 +388,15 @@ func (c *APIClient) decode(v interface{}, b []byte, contentType string) (err err
 		*s = string(b)
 		return nil
 	}
+	if f, ok := v.(**os.File); ok {
+		*f, err = ioutil.TempFile("", "HttpClientFile")
+		if err != nil {
+			return
+		}
+		_, err = (*f).Write(b)
+		_, err = (*f).Seek(0, io.SeekStart)
+		return
+	}
 	if xmlCheck.MatchString(contentType) {
 		if err = xml.Unmarshal(b, v); err != nil {
 			return err