#3904 Inheritance support java client retrofit gson (#4729)

* merge with master

* remove zoo specific artifact names

* fix duplicate doublequote

* #3904 add samples for retrofit2

* #3904 clean json field retrieval

* #3904 allow non-abstract parent class

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/ApiClient.mustache

@@ -2,6 +2,7 @@ package {{invokerPackage}};
 
 import com.google.gson.Gson;
 import com.google.gson.JsonParseException;
+import com.google.gson.JsonElement;
 import okhttp3.Interceptor;
 import okhttp3.OkHttpClient;
 import okhttp3.RequestBody;
@@ -39,6 +40,7 @@ import java.time.format.DateTimeFormatter;
 {{/java8}}
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.HashMap;
 
 public class ApiClient {
 

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/JSON.mustache

@@ -9,6 +9,9 @@ import com.google.gson.TypeAdapter;
 import com.google.gson.internal.bind.util.ISO8601Utils;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
+import com.google.gson.JsonElement;
+import io.gsonfire.GsonFireBuilder;
+import io.gsonfire.TypeSelector;
 {{#joda}}
 import org.joda.time.DateTime;
 import org.joda.time.LocalDate;
@@ -22,6 +25,8 @@ import org.threeten.bp.OffsetDateTime;
 import org.threeten.bp.format.DateTimeFormatter;
 {{/threetenbp}}
 
+import {{modelPackage}}.*;
+
 import java.io.IOException;
 import java.io.StringReader;
 import java.lang.reflect.Type;
@@ -34,6 +39,8 @@ import java.time.OffsetDateTime;
 import java.time.format.DateTimeFormatter;
 {{/java8}}
 import java.util.Date;
+import java.util.Map;
+import java.util.HashMap;
 
 public class JSON {
     private Gson gson;
@@ -48,8 +55,45 @@ public class JSON {
     private LocalDateTypeAdapter localDateTypeAdapter = new LocalDateTypeAdapter();
     {{/jsr310}}
 
+    public static GsonBuilder createGson() {
+        GsonFireBuilder fireBuilder = new GsonFireBuilder()
+        {{#parent}}
+          .registerTypeSelector({{classname}}.class, new TypeSelector() {
+            @Override
+            public Class getClassForElement(JsonElement readElement) {
+                Map classByDiscriminatorValue = new HashMap();
+                {{#children}}
+                classByDiscriminatorValue.put("{{name}}".toUpperCase(), {{classname}}.class);
+                {{/children}}
+                classByDiscriminatorValue.put("{{classname}}".toUpperCase(), {{classname}}.class);
+                return getClassByDiscriminator(
+                            classByDiscriminatorValue,
+                            getDiscriminatorValue(readElement, "{{discriminator}}"));
+            }
+          })
+        {{/parent}}
+        ;
+        return fireBuilder.createGsonBuilder();
+    }
+
+    private static String getDiscriminatorValue(JsonElement readElement, String discriminatorField) {
+        JsonElement element = readElement.getAsJsonObject().get(discriminatorField);
+        if(null == element) {
+            throw new IllegalArgumentException("missing discriminator field: <" + discriminatorField + ">");
+        }
+        return element.getAsString();
+    }
+
+    private static Class getClassByDiscriminator(Map classByDiscriminatorValue, String discriminatorValue) {
+        Class clazz = (Class) classByDiscriminatorValue.get(discriminatorValue.toUpperCase());
+        if(null == clazz) {
+            throw new IllegalArgumentException("cannot determine model class of name: <" + discriminatorValue + ">");
+        }
+        return clazz;
+    }
+
     public JSON() {
-        gson = new GsonBuilder()
+        gson = createGson()
             .registerTypeAdapter(Date.class, dateTypeAdapter)
             .registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter)
             {{#joda}}

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/build.gradle.mustache

@@ -126,6 +126,7 @@ ext {
     {{#threetenbp}}
     threetenbp_version = "1.3.5"
     {{/threetenbp}}
+    json_fire_version = "1.8.0"
 }
 
 dependencies {
@@ -142,6 +143,7 @@ dependencies {
     {{/useRxJava2}}
     compile "io.swagger:swagger-annotations:$swagger_annotations_version"
     compile "org.apache.oltu.oauth2:org.apache.oltu.oauth2.client:$oltu_version"
+    compile "io.gsonfire:gson-fire:$json_fire_version"
     {{#joda}}
     compile "joda-time:joda-time:$jodatime_version"
     {{/joda}}

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/build.sbt.mustache

@@ -45,6 +45,7 @@ lazy val root = (project in file(".")).
       {{#threetenbp}}
       "org.threeten" % "threetenbp" % "1.3.5" % "compile",
       {{/threetenbp}}
+      "io.gsonfire" % "gson-fire" % "1.8.0" % "compile",
       "junit" % "junit" % "4.12" % "test",
       "com.novocode" % "junit-interface" % "0.11" % "test"
     )

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/pom.mustache

@@ -194,6 +194,11 @@
       <artifactId>org.apache.oltu.oauth2.client</artifactId>
       <version>${oltu-version}</version>
     </dependency>
+    <dependency>
+      <groupId>io.gsonfire</groupId>
+      <artifactId>gson-fire</artifactId>
+      <version>${gson-fire-version}</version>
+    </dependency>
     {{#joda}}
     <dependency>
       <groupId>joda-time</groupId>
@@ -300,6 +305,7 @@
     <java.version>{{#java8}}1.8{{/java8}}{{^java8}}1.7{{/java8}}</java.version>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>
+    <gson-fire-version>1.8.0</gson-fire-version>
     <swagger-core-version>1.5.15</swagger-core-version>
     {{#usePlayWS}}
     {{#play24}}