set interface with discriminator as parent

If a composed model (allOf) doesn't have any parent and one of its interface has a discriminator field, then set this interface as parent.

See #2096
See https://github.com/swagger-api/swagger-parser/pull/246

modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java

@@ -1195,7 +1195,35 @@ public class DefaultCodegen {
                 allRequired = null;
             }
             // parent model
-            final RefModel parent = (RefModel) composed.getParent();
+            RefModel parent = (RefModel) composed.getParent();
+
+            // interfaces (intermediate models)
+            if (composed.getInterfaces() != null) {
+                if (m.interfaces == null)
+                    m.interfaces = new ArrayList<String>();
+                for (RefModel _interface : composed.getInterfaces()) {
+                    Model interfaceModel = null;
+                    if (allDefinitions != null) {
+                        interfaceModel = allDefinitions.get(_interface.getSimpleRef());
+                    }
+                    // set first interface with discriminator found as parent
+                    if (parent == null && interfaceModel instanceof ModelImpl && ((ModelImpl) interfaceModel).getDiscriminator() != null) {
+                        parent = _interface;
+                    } else {
+                        final String interfaceRef = toModelName(_interface.getSimpleRef());
+                        m.interfaces.add(interfaceRef);
+                        addImport(m, interfaceRef);
+                        if (allDefinitions != null) {
+                            if (supportsInheritance) {
+                                addProperties(allProperties, allRequired, interfaceModel, allDefinitions);
+                            } else {
+                                addProperties(properties, required, interfaceModel, allDefinitions);
+                            }
+                        }
+                    }
+                }
+            }
+
             if (parent != null) {
                 final String parentRef = parent.getSimpleRef();
                 m.parentSchema = parentRef;
@@ -1210,24 +1238,7 @@ public class DefaultCodegen {
                     }
                 }
             }
-            // interfaces (intermediate models)
+
-            if (composed.getInterfaces() != null) {
-                if (m.interfaces == null)
-                    m.interfaces = new ArrayList<String>();
-                for (RefModel _interface : composed.getInterfaces()) {
-                    final String interfaceRef = toModelName(_interface.getSimpleRef());
-                    m.interfaces.add(interfaceRef);
-                    addImport(m, interfaceRef);
-                    if (allDefinitions != null) {
-                        final Model interfaceModel = allDefinitions.get(_interface.getSimpleRef());
-                        if (supportsInheritance) {
-                            addProperties(allProperties, allRequired, interfaceModel, allDefinitions);
-                        } else {
-                            addProperties(properties, required, interfaceModel, allDefinitions);
-                        }
-                    }
-                }
-            }
             // child model (properties owned by the model itself)
             Model child = composed.getChild();
             if (child != null && child instanceof RefModel && allDefinitions != null) {

modules/swagger-codegen/src/test/java/io/swagger/codegen/java/JavaInheritanceTest.java

@@ -13,10 +13,14 @@ import com.google.common.collect.Sets;
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+
 public class JavaInheritanceTest {
 
     @SuppressWarnings("static-method")
-    @Test(description = "convert a composed model")
+    @Test(description = "convert a composed model with parent")
     public void javaInheritanceTest() {
         final Model model = new ComposedModel().parent(new RefModel("Base"))
                 .child(new ModelImpl().additionalProperties(new StringProperty()));
@@ -29,4 +33,26 @@ public class JavaInheritanceTest {
         Assert.assertEquals(cm.parent, "Base");
         Assert.assertEquals(cm.imports, Sets.newHashSet("Base"));
     }
+
+    @SuppressWarnings("static-method")
+    @Test(description = "convert a composed model with discriminator")
+    public void javaInheritanceWithDiscriminatorTest() {
+        ModelImpl base = new ModelImpl();
+        base.setDiscriminator("disc");
+
+        final Model model = new ComposedModel()
+                .interfaces(Arrays.asList(new RefModel("Base")))
+                .child(new ModelImpl().additionalProperties(new StringProperty()));
+
+        final Map<String, Model> allDefinitions = new HashMap<String, Model>();
+        allDefinitions.put("Base", base);
+
+        final DefaultCodegen codegen = new JavaClientCodegen();
+        final CodegenModel cm = codegen.fromModel("sample", model, allDefinitions);
+
+        Assert.assertEquals(cm.name, "sample");
+        Assert.assertEquals(cm.classname, "Sample");
+        Assert.assertEquals(cm.parent, "Base");
+        Assert.assertEquals(cm.imports, Sets.newHashSet("Base"));
+    }
 }

modules/swagger-codegen/src/test/java/io/swagger/codegen/javascript/JavaScriptInheritanceTest.java

@@ -51,7 +51,7 @@ public class JavaScriptInheritanceTest {
         Assert.assertEquals(cm.vars.size(), 1);
         Assert.assertEquals(cm.vars.get(0).name, "childProp");
         Assert.assertEquals(cm.allVars.size(), 4);
-        String[] allVars = {"baseProp", "intf1Prop", "intf2Prop", "childProp"};
+        String[] allVars = {"intf1Prop", "intf2Prop", "baseProp", "childProp"};
         for (int i = 0; i < allVars.length; i++) {
             Assert.assertEquals(cm.allVars.get(i).name, allVars[i]);
         }
@@ -91,7 +91,7 @@ public class JavaScriptInheritanceTest {
         Assert.assertEquals(cm.imports, Sets.newHashSet("Base", "Interface1", "Interface2"));
         Assert.assertEquals(cm.vars.size(), 4);
         Assert.assertEquals(cm.allVars.size(), 4);
-        String[] allVars = {"baseProp", "intf1Prop", "intf2Prop", "childProp"};
+        String[] allVars = {"intf1Prop", "intf2Prop", "baseProp", "childProp"};
         for (int i = 0; i < allVars.length; i++) {
             Assert.assertEquals(cm.vars.get(i).name, allVars[i]);
             Assert.assertEquals(cm.allVars.get(i).name, allVars[i]);