Move check into rpc/init

* Add link to GitHub Issue

rpc/cty_encode.go

@@ -4,16 +4,10 @@
 package rpc
 
 import (
-	"encoding/gob"
-
 	"github.com/zclconf/go-cty/cty"
 	"github.com/zclconf/go-cty/cty/json"
 )
 
-// Test that cty types implement the gob.GobEncoder interface.
-// Support for encoding/gob was removed in github.com/zclconf/go-cty@v1.11.0.
-var _ gob.GobEncoder = cty.Value{}
-
 // cty.Value is does not know how to encode itself through the wire so we
 // transform it to bytes.
 func encodeCTYValues(config []interface{}) ([]interface{}, error) {

rpc/init.go

@@ -9,7 +9,16 @@ underpins the packer server that all plugins must implement.
 */
 package rpc
 
-import "encoding/gob"
+import (
+	"encoding/gob"
+
+	"github.com/zclconf/go-cty/cty"
+)
+
+// Test that cty types implement the gob.GobEncoder interface.
+// Support for encoding/gob was removed in github.com/zclconf/go-cty@v1.11.0.
+// Refer to issue https://github.com/hashicorp/packer-plugin-sdk/issues/187
+var _ gob.GobEncoder = cty.Value{}
 
 func init() {
 	gob.Register(new(map[string]string))