dynamite: Support objects with unknown key names

packages/dynamite/lib/src/models/schema.dart

@@ -60,7 +60,10 @@ class Schema {
 
   final Schema? items;
 
-  final bool? additionalProperties;
+  @JsonKey(
+    fromJson: _parseAdditionalProperties,
+  )
+  final Schema? additionalProperties;
 
   final String? contentMediaType;
 
@@ -72,3 +75,21 @@ class Schema {
 
   bool get isContentString => type == 'string' && (contentMediaType?.isNotEmpty ?? false) && contentSchema != null;
 }
+
+class EmptySchema extends Schema {}
+
+Schema? _parseAdditionalProperties(final dynamic data) {
+  if (data == null) {
+    return null;
+  }
+
+  if (data is bool) {
+    return data ? EmptySchema() : null;
+  }
+
+  if (data is Map<String, dynamic>) {
+    return Schema.fromJson(data);
+  }
+
+  throw Exception('Can not parse additionalProperties from $data');
+}

packages/dynamite/lib/src/models/schema.g.dart

@@ -46,7 +46,7 @@ Schema _$SchemaFromJson(Map<String, dynamic> json) {
     ),
     required: (json['required'] as List<dynamic>?)?.map((e) => e as String).toList(),
     items: json['items'] == null ? null : Schema.fromJson(json['items'] as Map<String, dynamic>),
-    additionalProperties: json['additionalProperties'] as bool?,
+    additionalProperties: _parseAdditionalProperties(json['additionalProperties']),
     contentMediaType: json['contentMediaType'] as String?,
     contentSchema:
         json['contentSchema'] == null ? null : Schema.fromJson(json['contentSchema'] as Map<String, dynamic>),
@@ -78,7 +78,7 @@ Map<String, dynamic> _$SchemaToJson(Schema instance) {
   writeNotNull('properties', instance.properties?.map((k, e) => MapEntry(k, e.toJson())));
   writeNotNull('required', instance.required);
   writeNotNull('items', instance.items?.toJson());
-  writeNotNull('additionalProperties', instance.additionalProperties);
+  writeNotNull('additionalProperties', instance.additionalProperties?.toJson());
   writeNotNull('contentMediaType', instance.contentMediaType);
   writeNotNull('contentSchema', instance.contentSchema?.toJson());
   writeNotNull('discriminator', instance.discriminator?.toJson());

packages/dynamite/lib/src/openapi_builder.dart

@@ -1082,7 +1082,7 @@ TypeResult resolveObject(
               refer('JsonSerializable').call(
                 [],
                 {
-                  if (schema.additionalProperties ?? false) ...{
+                  if (schema.additionalProperties != null) ...{
                     'disallowUnrecognizedKeys': refer('false'),
                   },
                   if (extraJsonSerializableValues != null) ...{
@@ -1543,11 +1543,25 @@ TypeResult resolveType(
         break;
       case 'object':
         if (schema.properties == null) {
-          if (schema.additionalProperties ?? false) {
+          if (schema.additionalProperties != null) {
+            if (schema.additionalProperties is EmptySchema) {
               result = TypeResultMap(
                 'Map<String, dynamic>',
                 TypeResultBase('dynamic'),
               );
+            } else {
+              final subResult = resolveType(
+                spec,
+                state,
+                identifier,
+                schema.additionalProperties!,
+                extraJsonSerializableValues: extraJsonSerializableValues,
+              );
+              result = TypeResultMap(
+                'Map<String, ${subResult.name}>',
+                TypeResultBase('dynamic'),
+              );
+            }
             break;
           }
           result = TypeResultBase('dynamic');