fix for issue swagger-api#1018

Author: gracekarina

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/InlineModelResolver.java

@@ -422,6 +422,8 @@ public Schema modelFromProperty(ArraySchema object, @SuppressWarnings("unused")
     public Schema modelFromProperty(ObjectSchema object, String path) {
         String description = object.getDescription();
         String example = null;
+        List<String> requiredList = object.getRequired();
+
 
         Object obj = object.getExample();
         if (obj != null) {
@@ -437,6 +439,7 @@ public Schema modelFromProperty(ObjectSchema object, String path) {
         model.setName(name);
         model.setXml(xml);
         model.setType(object.getType());
+        model.setRequired(requiredList);
 
         if (properties != null) {
             flattenProperties(properties, path);

modules/swagger-parser-v3/src/test/java/io/swagger/v3/parser/util/InlineModelResolverTest.java

@@ -2,6 +2,7 @@
 
 
 
+import io.swagger.v3.core.util.Yaml;
 import io.swagger.v3.oas.models.Components;
 import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.Operation;
@@ -32,6 +33,17 @@
 @SuppressWarnings("static-method")
 public class InlineModelResolverTest {
 
+    @Test
+    public void testIssue1018() throws Exception {
+        ParseOptions options = new ParseOptions();
+        options.setFlatten(true);
+        OpenAPI openAPI = new OpenAPIV3Parser().read("flatten.json",null, options);
+
+        assertNotNull(openAPI);
+        assertNotNull(openAPI.getComponents().getSchemas().get("ReturnInformation_manufacturer_signin_credentials").getRequired());
+    }
+
+
     @Test
     public void testIssue705() throws Exception {
         ParseOptions options = new ParseOptions();

modules/swagger-parser-v3/src/test/resources/flatten.json

@@ -2,6 +2,26 @@
   "openapi" : "3.0.1",
   "components" : {
     "schemas" : {
+      "ReturnInformation": {
+        "type": "object",
+        "properties": {
+          "manufacturer_signin_credentials": {
+            "type": "object",
+            "properties": {
+              "login": {
+                "type": "string"
+              },
+              "password": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "login",
+              "password"
+            ]
+          }
+        }
+      },
       "User" : {
         "required" : [ "address" ],
         "properties" : {