refactor!: unexport JSON encode/decode

These functions are only needed in order to fulfill goavro interface and
has nothing to do with writing OCR files. Unexporting them allows us to
change to another library which does not need the intermediate JSON but
writes binary directly.

README.md

@@ -97,43 +97,6 @@ func ExampleUnmarshaler() {
 }
 ```
 
-### `protoavro.EncodeJSON` + `protoavro.DecodeJSON`
-
-Avro JSON encoding of arbitrary protobuf messages.
-
-```go
-func ExampleEncodeJSON() {
-    msg := &library.Book{
-        Name:   "books/1",
-        Author: "J. K. Rowling",
-        Title:  "Harry Potter",
-        Read:   true,
-    }
-    encoded, err := protoavro.EncodeJSON(msg)
-    if err != nil {
-        panic(err)
-    }
-    var decoded library.Book
-    if err := protoavro.DecodeJSON(encoded, &decoded); err != nil {
-        panic(err)
-    }
-
-    encodedBytes, err := json.MarshalIndent(encoded, "", "\t")
-    fmt.Println(string(encodedBytes))
-    fmt.Println(cmp.Equal(msg, &decoded, protocmp.Transform()))
-    // Output:
-    // {
-    //	"google.example.library.v1.Book": {
-    //		"author": "J. K. Rowling",
-    //		"name": "books/1",
-    //		"read": true,
-    //		"title": "Harry Potter"
-    //	}
-    // }
-    // true
-}
-```
-
 ### Mapping
 
 **Messages** are mapped as nullable records in Avro. Fields will have the same casing as in the protobuf descriptor.

encoding/protoavro/decode.go

@@ -7,9 +7,9 @@ import (
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
-// DecodeJSON decodes the JSON encoded avro data and places the
+// decodeJSON decodes the JSON encoded avro data and places the
 // result in msg.
-func DecodeJSON(data interface{}, msg proto.Message) error {
+func decodeJSON(data interface{}, msg proto.Message) error {
 	return decodeMessage(data, msg.ProtoReflect())
 }
 

encoding/protoavro/encoding_test.go

@@ -536,7 +536,7 @@ func Test_JSON(t *testing.T) {
 
 			next := proto.Clone(tt.msg)
 			proto.Reset(next)
-			assert.NilError(t, DecodeJSON(got, next))
+			assert.NilError(t, decodeJSON(got, next))
 			assert.DeepEqual(t, tt.msg, next, protocmp.Transform())
 		})
 	}

encoding/protoavro/unmarshal.go

@@ -35,7 +35,7 @@ func (m *Unmarshaler) Unmarshal(message proto.Message) error {
 	if err != nil {
 		return fmt.Errorf("read message: %w", err)
 	}
-	if err := DecodeJSON(data, message); err != nil {
+	if err := decodeJSON(data, message); err != nil {
 		return fmt.Errorf("decode message: %w", err)
 	}
 	return nil