flatten spec converted from 2.0 when option is true

Author: frantuma

modules/swagger-parser-v2-converter/src/main/java/io/swagger/v3/parser/converter/SwaggerConverter.java

@@ -33,6 +33,7 @@
 import io.swagger.parser.util.SwaggerDeserializationResult;
 import io.swagger.v3.core.util.Json;
 import io.swagger.v3.core.util.PrimitiveType;
+import io.swagger.v3.core.util.Yaml;
 import io.swagger.v3.oas.models.Components;
 import io.swagger.v3.oas.models.ExternalDocumentation;
 import io.swagger.v3.oas.models.OpenAPI;
@@ -60,6 +61,7 @@
 import io.swagger.v3.oas.models.security.SecurityScheme;
 import io.swagger.v3.oas.models.servers.Server;
 import io.swagger.v3.oas.models.tags.Tag;
+import io.swagger.v3.parser.OpenAPIV3Parser;
 import io.swagger.v3.parser.core.extensions.SwaggerParserExtension;
 import io.swagger.v3.parser.core.models.AuthorizationValue;
 import io.swagger.v3.parser.core.models.ParseOptions;
@@ -107,7 +109,23 @@ public SwaggerParseResult readContents(String swaggerAsString, List<Authorizatio
                 result.setSwagger(resolved);
             }
         }
-        return convert(result);
+        SwaggerParseResult out = convert(result);
+        if (out != null && options != null && options.isFlatten()) {
+            try {
+                SwaggerParseResult resultV3 = new OpenAPIV3Parser().readContents(Yaml.pretty(out.getOpenAPI()), auth, options);
+                out.setOpenAPI(resultV3.getOpenAPI());
+                if (out.getMessages() != null) {
+                    out.getMessages().addAll(resultV3.getMessages());
+                    out.messages(out.getMessages().stream()
+                            .distinct()
+                            .collect(Collectors.toList()));
+                } else {
+                    out.messages(resultV3.getMessages());
+                }
+            } catch (Exception ignore) {}
+        }
+        return out;
+
     }
 
     public List<io.swagger.models.auth.AuthorizationValue> convert(List<AuthorizationValue> auths) {

modules/swagger-parser/src/test/java/io/swagger/parser/OpenAPIParserTest.java

@@ -133,6 +133,48 @@ public void test30Url() {
         assertEquals(result.getOpenAPI().getOpenapi(), "3.0.1");
     }
 
+    @Test
+    public void testConverterWithFlatten() {
+        String yaml = "swagger: \"2.0\"\n" +
+                "info:\n" +
+                "  description: \"Foo\"\n" +
+                "  version: \"1.0.0\"\n" +
+                "host: \"something.com\"\n" +
+                "basePath: \"/\"\n" +
+                "schemes:\n" +
+                "  - \"https\"\n" +
+                "consumes:\n" +
+                "  - \"application/json\"\n" +
+                "produces:\n" +
+                "  - \"application/json\"\n" +
+                "paths:\n" +
+                "  /example:\n" +
+                "    get:\n" +
+                "      responses:\n" +
+                "        200:\n" +
+                "          description: \"OK\"\n" +
+                "          schema:\n" +
+                "            $ref: \"#/definitions/Foo\"\n" +
+                "    parameters: []\n" +
+                "definitions:\n" +
+                "  Foo:\n" +
+                "    type: \"object\"\n" +
+                "    required:\n" +
+                "    properties:\n" +
+                "      nested:\n" +
+                "        type: \"object\"\n" +
+                "        properties:\n" +
+                "          color:\n" +
+                "            type: \"string\"";
+
+        ParseOptions options = new ParseOptions();
+        options.setResolve(true);
+        options.setFlatten(true);
+        SwaggerParseResult result = new OpenAPIParser().readContents(yaml, null, options);
+        OpenAPI openAPI = result.getOpenAPI();
+        assertEquals(openAPI.getComponents().getSchemas().size(), 2);
+    }
+
     @Test
     public void test30() {
         String json =