config: Preserve intentionally empty maps

Closes #14944

parser/lowercase_camel_json.go

@@ -107,29 +107,33 @@ func (c ReplacingJSONMarshaller) MarshalJSON() ([]byte, error) {
 		if err != nil {
 			return nil, err
 		}
-		var removeZeroVAlues func(m map[string]any)
-		removeZeroVAlues = func(m map[string]any) {
+		var removeZeroValues func(m map[string]any)
+		removeZeroValues = func(m map[string]any) {
 			for k, v := range m {
 				if !hreflect.IsMap(v) && !hreflect.IsTruthful(v) {
 					delete(m, k)
 				} else {
 					switch vv := v.(type) {
 					case map[string]any:
-						removeZeroVAlues(vv)
+						if len(vv) == 0 {
+							// Keep intentionally empty map.
+							continue
+						}
+						removeZeroValues(vv)
 						if len(vv) == 0 {
 							delete(m, k)
 						}
 					case []any:
 						for _, vvv := range vv {
 							if m, ok := vvv.(map[string]any); ok {
-								removeZeroVAlues(m)
+								removeZeroValues(m)
 							}
 						}
 					}
 				}
 			}
 		}
-		removeZeroVAlues(m)
+		removeZeroValues(m)
 		converted, err = json.Marshal(m)
 
 	}

testscripts/commands/config.txt

@@ -6,6 +6,7 @@ stdout 'Display project configuration'
 
 hugo config
 stdout 'baseurl = .https://example.com/'
+stdout '\[contenttypes\.'
 hugo config --format json
 stdout '\"baseurl\": \"https://example.com/\",'