Same object not allowed within same api-request

Description

If the same object are placed in several places within an API request there will only one occurrence produced by the ExampleGenerator.
There is an infinite loop in the Junit test for ExampleGenerator that is inhibited by allowing only one occurence of an object within an example.

Swagger-codegen version

2.2.2-SNAPSHOT

Swagger declaration file content or url

```

QueryUserGroups:
type: object
title: QueryUserGroups
properties:
status:
type: string
data:
type: object
title: QueryUserGroups
properties:
userGroups:
type: array
items:
type: string
required:
- userGroups
required:

• status

Command line used for generation

java -jar swagger-codegen/modules/swagger-codegen-cli/target/swagger-codegen-cli.jar generate -l jaxrs-cxf -i api.yaml

Steps to reproduce

Related issues

Suggest a Fix

In DefaultGenerator.java:
public Object resolveModelToExample(String name, String mediaType, Model model, Set processedModels) {
// if (processedModels.contains(name)) {
// return "";
// }

In ExampleGeneratorTest.java:
@@ -26,11 +27,17 @@ public class ExampleGeneratorTest {
final String JSON = "application/json";
final String XML = "application/xml";
final String nodeType = "Node";

•    final RefProperty ref = new RefProperty(nodeType);
  

•    final String nodeTypeParent = "NodeParent";
  

•    final String nodeTypeChild = "NodeChild";
  

•    final RefProperty refParent = new RefProperty(nodeTypeParent);
  

•    final RefProperty refChild = new RefProperty(nodeTypeChild);
  

•    final Model node = new ModelImpl().name(nodeType).property("name", new StringProperty())
  

•            .property("parent", ref)
  

•            .property("children", new ArrayProperty(ref))
  

•            .property("wrappedChildren", new ArrayProperty(ref).xml(new Xml().wrapped(true)));
  

•            .property("parent", refParent)
  

•            .property("children", new ArrayProperty(refChild))
  

•            .property("wrappedChildren", new ArrayProperty(refChild).xml(new Xml().wrapped(true)));
     final String pairType = "Pair";
     final ModelImpl pair = new ModelImpl().name(pairType);
     for (Map.Entry<String, String> item : ImmutableMap.of("first", "First", "second", "Second").entrySet()) {
  

In XmlExampleGenerator.java:
@@ -170,6 +169,9 @@ public class XmlExampleGenerator {
sb.append(closeTag(name));
}
}

•    if(sb.toString().equals("null")){
  

•        return "";
  

Start with resolveModelToExample in DefaultGenerator.java and the related cases in ExampleGeneratorTest.java; then inspect the XML path in XmlExampleGenerator.java. Run the ExampleGenerator tests and reproduce the nested repeated-object case from the issue. Done means repeated object references are represented in the generated example without an infinite loop, with regression coverage for the behavior.