Concatenate if file already exist

main.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/golang/protobuf/proto"
 	"github.com/golang/protobuf/protoc-gen-go/generator"
+	"github.com/golang/protobuf/protoc-gen-go/plugin"
 )
 
 func main() {
@@ -71,17 +72,32 @@ func main() {
 		}
 	}
 
+	tmplMap := make(map[string]*plugin_go.CodeGeneratorResponse_File)
+	concatOrAppend := func(file *plugin_go.CodeGeneratorResponse_File) {
+		if val, ok := tmplMap[*file.Name]; ok {
+			*val.Content += *file.Content
+		} else {
+			tmplMap[*file.Name] = file
+			g.Response.File = append(g.Response.File, file)
+		}
+	}
+
 	// Generate the encoders
 	for _, file := range g.Request.GetProtoFile() {
 		if all {
 			encoder := NewGenericTemplateBasedEncoder(templateDir, file, debug, destinationDir)
-			g.Response.File = append(g.Response.File, encoder.Files()...)
+			for _, tmpl := range encoder.Files() {
+				concatOrAppend(tmpl)
+			}
+
 			continue
 		}
 
 		for _, service := range file.GetService() {
 			encoder := NewGenericServiceTemplateBasedEncoder(templateDir, service, file, debug, destinationDir)
-			g.Response.File = append(g.Response.File, encoder.Files()...)
+			for _, tmpl := range encoder.Files() {
+				concatOrAppend(tmpl)
+			}
 		}
 	}