add helper methods to anyOf in java models (#7130)

modules/openapi-generator/src/main/resources/Java/libraries/jersey2/anyof_model.mustache

@@ -148,6 +148,14 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
         return {{classname}}.schemas;
     }
 
+    /**
+     * Set the instance that matches the anyOf child schema, check
+     * the instance parameter is valid against the anyOf child schemas:
+     * {{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}
+     *
+     * It could be an instance of the 'anyOf' schemas.
+     * The anyOf child schemas may themselves be a composed schema (allOf, anyOf, anyOf).
+     */
     @Override
     public void setActualInstance(Object instance) {
         {{#isNullable}}
@@ -166,4 +174,29 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
         {{/anyOf}}
         throw new RuntimeException("Invalid instance type. Must be {{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}");
     }
+
+    /**
+     * Get the actual instance, which can be the following:
+     * {{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}}
+     *
+     * @return The actual instance ({{#anyOf}}{{{.}}}{{^-last}}, {{/-last}}{{/anyOf}})
+     */
+    @Override
+    public Object getActualInstance() {
+        return super.getActualInstance();
+    }
+
+    {{#anyOf}}
+    /**
+     * Get the actual instance of `{{{.}}}`. If the actual instanct is not `{{{.}}}`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `{{{.}}}`
+     * @throws ClassCastException if the instance is not `{{{.}}}`
+     */
+    public {{{.}}} get{{{.}}}() throws ClassCastException {
+        return ({{{.}}})super.getActualInstance();
+    }
+
+    {{/anyOf}}
 }

samples/openapi3/client/petstore/java/jersey2-java8/src/main/java/org/openapitools/client/model/GmFruit.java

@@ -153,6 +153,14 @@ public class GmFruit extends AbstractOpenApiSchema {
         return GmFruit.schemas;
     }
 
+    /**
+     * Set the instance that matches the anyOf child schema, check
+     * the instance parameter is valid against the anyOf child schemas:
+     * Apple, Banana
+     *
+     * It could be an instance of the 'anyOf' schemas.
+     * The anyOf child schemas may themselves be a composed schema (allOf, anyOf, anyOf).
+     */
     @Override
     public void setActualInstance(Object instance) {
         if (JSON.isInstanceOf(Apple.class, instance, new HashSet<Class<?>>())) {
@@ -167,5 +175,39 @@ public class GmFruit extends AbstractOpenApiSchema {
 
         throw new RuntimeException("Invalid instance type. Must be Apple, Banana");
     }
+
+    /**
+     * Get the actual instance, which can be the following:
+     * Apple, Banana
+     *
+     * @return The actual instance (Apple, Banana)
+     */
+    @Override
+    public Object getActualInstance() {
+        return super.getActualInstance();
+    }
+
+    /**
+     * Get the actual instance of `Apple`. If the actual instanct is not `Apple`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Apple`
+     * @throws ClassCastException if the instance is not `Apple`
+     */
+    public Apple getApple() throws ClassCastException {
+        return (Apple)super.getActualInstance();
+    }
+
+    /**
+     * Get the actual instance of `Banana`. If the actual instanct is not `Banana`,
+     * the ClassCastException will be thrown.
+     *
+     * @return The actual instance of `Banana`
+     * @throws ClassCastException if the instance is not `Banana`
+     */
+    public Banana getBanana() throws ClassCastException {
+        return (Banana)super.getActualInstance();
+    }
+
 }