[Java] Enable discriminator recursive lookup (#5895)

* Adds addComposedMappedModels and testComposedSchemaOneOfDiscriminatorMap

* Requires that discriminators be required properties

* Strengthens discriminaotr validation, adds better error messages, adds schema oneof samples

* Adds oneOf and anyOf invalidDiscriminator tests

* Updates incorrect addOneOfInterfaceModel invocation

* Runs ensure-up-to-date

* Adds updates from Sebastien Rosset

* Removes newlines

* Uses df.isString

* Fixes tests be correctly setting df.isString

* Updates discriminatorExplicitMappingVerbose description per PR feedback

* Adds description of how mappedModels is populated

* enable discriminator lookup

* Adds the suggestion exception raising when a MappedModel mappingName is null

* Actually resolves merge conflicts

* Adds addComposedMappedModels and testComposedSchemaOneOfDiscriminatorMap

* Requires that discriminators be required properties

* Strengthens discriminaotr validation, adds better error messages, adds schema oneof samples

* Adds oneOf and anyOf invalidDiscriminator tests

* Updates incorrect addOneOfInterfaceModel invocation

* Runs ensure-up-to-date

* Adds updates from Sebastien Rosset

* Removes newlines

* Uses df.isString

* Fixes tests be correctly setting df.isString

* Updates discriminatorExplicitMappingVerbose description per PR feedback

* Adds description of how mappedModels is populated

* Adds the suggestion exception raising when a MappedModel mappingName is null

* Actually resolves merge conflicts

* Switches two methods to package private because they are needed for testing

* Allow nulls in MappedModel.getMappingName

* Address Jim Schubert review comments

* Updates CLI flag name to legacyDiscriminatorBehavior, default=true

* Change discriminator CLI option. Remove exception when mappingName is null value

* resolve merge conflicts

* Execute scripts under bin directory

Co-authored-by: Justin Black <justin.a.black@gmail.com>
Co-authored-by: William Cheng <wing328hk@gmail.com>

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/JSON.java

@@ -56,13 +56,41 @@ public class JSON {
                     @Override
                     public Class getClassForElement(JsonElement readElement) {
                         Map<String, Class> classByDiscriminatorValue = new HashMap<String, Class>();
-                        classByDiscriminatorValue.put("Dog", Dog.class);
-                        classByDiscriminatorValue.put("Cat", Cat.class);
                         classByDiscriminatorValue.put("BigCat", BigCat.class);
+                        classByDiscriminatorValue.put("Cat", Cat.class);
+                        classByDiscriminatorValue.put("Dog", Dog.class);
                         classByDiscriminatorValue.put("Animal", Animal.class);
                         return getClassByDiscriminator(classByDiscriminatorValue,
                                 getDiscriminatorValue(readElement, "className"));
                     }
+          })
+                .registerTypeSelector(BigCat.class, new TypeSelector() {
+                    @Override
+                    public Class getClassForElement(JsonElement readElement) {
+                        Map<String, Class> classByDiscriminatorValue = new HashMap<String, Class>();
+                        classByDiscriminatorValue.put("BigCat", BigCat.class);
+                        return getClassByDiscriminator(classByDiscriminatorValue,
+                                getDiscriminatorValue(readElement, "className"));
+                    }
+          })
+                .registerTypeSelector(Cat.class, new TypeSelector() {
+                    @Override
+                    public Class getClassForElement(JsonElement readElement) {
+                        Map<String, Class> classByDiscriminatorValue = new HashMap<String, Class>();
+                        classByDiscriminatorValue.put("BigCat", BigCat.class);
+                        classByDiscriminatorValue.put("Cat", Cat.class);
+                        return getClassByDiscriminator(classByDiscriminatorValue,
+                                getDiscriminatorValue(readElement, "className"));
+                    }
+          })
+                .registerTypeSelector(Dog.class, new TypeSelector() {
+                    @Override
+                    public Class getClassForElement(JsonElement readElement) {
+                        Map<String, Class> classByDiscriminatorValue = new HashMap<String, Class>();
+                        classByDiscriminatorValue.put("Dog", Dog.class);
+                        return getClassByDiscriminator(classByDiscriminatorValue,
+                                getDiscriminatorValue(readElement, "className"));
+                    }
           })
         ;
         GsonBuilder builder = fireBuilder.createGsonBuilder();

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Animal.java

@@ -23,6 +23,9 @@ import com.google.gson.stream.JsonWriter;
 import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
 import java.io.IOException;
+import org.openapitools.client.model.BigCat;
+import org.openapitools.client.model.Cat;
+import org.openapitools.client.model.Dog;
 
 /**
  * Animal

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/BigCat.java

@@ -30,6 +30,7 @@ import org.openapitools.client.model.Cat;
  * BigCat
  */
 
+
 public class BigCat extends Cat {
   /**
    * Gets or Sets kind
@@ -86,6 +87,9 @@ public class BigCat extends Cat {
   @SerializedName(SERIALIZED_NAME_KIND)
   private KindEnum kind;
 
+  public BigCat() {
+    this.className = this.getClass().getSimpleName();
+  }
 
   public BigCat kind(KindEnum kind) {
     

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Cat.java

@@ -24,17 +24,22 @@ import io.swagger.annotations.ApiModel;
 import io.swagger.annotations.ApiModelProperty;
 import java.io.IOException;
 import org.openapitools.client.model.Animal;
+import org.openapitools.client.model.BigCat;
 import org.openapitools.client.model.CatAllOf;
 
 /**
  * Cat
  */
 
+
 public class Cat extends Animal {
   public static final String SERIALIZED_NAME_DECLAWED = "declawed";
   @SerializedName(SERIALIZED_NAME_DECLAWED)
   private Boolean declawed;
 
+  public Cat() {
+    this.className = this.getClass().getSimpleName();
+  }
 
   public Cat declawed(Boolean declawed) {
     

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Dog.java

@@ -30,11 +30,15 @@ import org.openapitools.client.model.DogAllOf;
  * Dog
  */
 
+
 public class Dog extends Animal {
   public static final String SERIALIZED_NAME_BREED = "breed";
   @SerializedName(SERIALIZED_NAME_BREED)
   private String breed;
 
+  public Dog() {
+    this.className = this.getClass().getSimpleName();
+  }
 
   public Dog breed(String breed) {