Add pkg/compare/Path.MarshalJSON function to implement json.Marshaler interface (#18)

Issue aws-controllers-k8s/community#772

Description of changes:
- Add `MarshalJSON` function method to help encoding `pkg/comapare.Path` unexported fields



By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: a-hilaly

pkg/compare/path.go

@@ -13,14 +13,32 @@
 
 package compare
 
-import "strings"
+import (
+	"encoding/json"
+	"strings"
+)
 
 // Path provides a JSONPath-like struct and field-member "route" to a
-// particular field within a compared struct
+// particular field within a compared struct. Path implements json.Marshaler
+// interface.
 type Path struct {
 	parts []string
 }
 
+// MarshalJSON returns the JSON encoding of a Path object.
+func (p Path) MarshalJSON() ([]byte, error) {
+	// Since json.Marshall doesn't encode unexported struct fields we have to
+	// copy the Path instance into a new struct object with exported fields.
+	// See https://github.com/aws-controllers-k8s/community/issues/772
+	return json.Marshal(
+		struct {
+			Parts []string
+		}{
+			p.parts,
+		},
+	)
+}
+
 // Push adds a new part to the Path.
 func (p Path) Push(part string) {
 	p.parts = append(p.parts, part)