[java] implement #18032 add builder pattern to java client and spring generator (#18650)

* add builder pattern to java client and spring generator

* regenerate samples

* update doc

---------

Co-authored-by: jpfinne <jeanpaul@finne.be>

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Addressable.java

@@ -104,5 +104,69 @@ public class Addressable {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder {
+
+    private Addressable instance;
+
+    public Builder() {
+      this(new Addressable());
+    }
+
+    protected Builder(Addressable instance) {
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Addressable value) { 
+      this.instance.setHref(value.href);
+      this.instance.setId(value.id);
+      return this;
+    }
+
+    public Addressable.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    public Addressable.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    /**
+    * returns a built Addressable instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Addressable build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Addressable.Builder builder() {
+    return new Addressable.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Addressable.Builder toBuilder() {
+    Addressable.Builder builder = new Addressable.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Apple.java

@@ -119,5 +119,69 @@ public class Apple implements Fruit {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder {
+
+    private Apple instance;
+
+    public Builder() {
+      this(new Apple());
+    }
+
+    protected Builder(Apple instance) {
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Apple value) { 
+      this.instance.setSeeds(value.seeds);
+      this.instance.setFruitType(value.fruitType);
+      return this;
+    }
+
+    public Apple.Builder seeds(Integer seeds) {
+      this.instance.seeds(seeds);
+      return this;
+    }
+    
+    public Apple.Builder fruitType(FruitType fruitType) {
+      this.instance.fruitType(fruitType);
+      return this;
+    }
+    
+    /**
+    * returns a built Apple instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Apple build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Apple.Builder builder() {
+    return new Apple.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Apple.Builder toBuilder() {
+    Apple.Builder builder = new Apple.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Banana.java

@@ -119,5 +119,69 @@ public class Banana implements Fruit {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder {
+
+    private Banana instance;
+
+    public Builder() {
+      this(new Banana());
+    }
+
+    protected Builder(Banana instance) {
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Banana value) { 
+      this.instance.setLength(value.length);
+      this.instance.setFruitType(value.fruitType);
+      return this;
+    }
+
+    public Banana.Builder length(Integer length) {
+      this.instance.length(length);
+      return this;
+    }
+    
+    public Banana.Builder fruitType(FruitType fruitType) {
+      this.instance.fruitType(fruitType);
+      return this;
+    }
+    
+    /**
+    * returns a built Banana instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Banana build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Banana.Builder builder() {
+    return new Banana.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Banana.Builder toBuilder() {
+    Banana.Builder builder = new Banana.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Bar.java

@@ -191,5 +191,108 @@ public class Bar extends Entity implements BarRefOrValue {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends Entity.Builder {
+
+    private Bar instance;
+
+    public Builder() {
+      this(new Bar());
+    }
+
+    protected Builder(Bar instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Bar value) { 
+      super.copyOf(instance);
+      this.instance.setId(value.id);
+      this.instance.setBarPropA(value.barPropA);
+      this.instance.setFooPropB(value.fooPropB);
+      this.instance.setFoo(value.foo);
+      return this;
+    }
+
+    public Bar.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    public Bar.Builder barPropA(String barPropA) {
+      this.instance.barPropA(barPropA);
+      return this;
+    }
+    
+    public Bar.Builder fooPropB(String fooPropB) {
+      this.instance.fooPropB(fooPropB);
+      return this;
+    }
+    
+    public Bar.Builder foo(FooRefOrValue foo) {
+      this.instance.foo(foo);
+      return this;
+    }
+    
+    @Override
+    public Bar.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public Bar.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public Bar.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public Bar.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built Bar instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Bar build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Bar.Builder builder() {
+    return new Bar.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Bar.Builder toBuilder() {
+    Bar.Builder builder = new Bar.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/BarCreate.java

@@ -173,5 +173,108 @@ public class BarCreate extends Entity {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends Entity.Builder {
+
+    private BarCreate instance;
+
+    public Builder() {
+      this(new BarCreate());
+    }
+
+    protected Builder(BarCreate instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(BarCreate value) { 
+      super.copyOf(instance);
+      this.instance.setBarPropA(value.barPropA);
+      this.instance.setFooPropB(value.fooPropB);
+      this.instance.setFoo(value.foo);
+      return this;
+    }
+
+    public BarCreate.Builder barPropA(String barPropA) {
+      this.instance.barPropA(barPropA);
+      return this;
+    }
+    
+    public BarCreate.Builder fooPropB(String fooPropB) {
+      this.instance.fooPropB(fooPropB);
+      return this;
+    }
+    
+    public BarCreate.Builder foo(FooRefOrValue foo) {
+      this.instance.foo(foo);
+      return this;
+    }
+    
+    @Override
+    public BarCreate.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public BarCreate.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public BarCreate.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public BarCreate.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public BarCreate.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built BarCreate instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public BarCreate build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static BarCreate.Builder builder() {
+    return new BarCreate.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public BarCreate.Builder toBuilder() {
+    BarCreate.Builder builder = new BarCreate.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/BarRef.java

@@ -107,5 +107,102 @@ public class BarRef extends EntityRef implements BarRefOrValue {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends EntityRef.Builder {
+
+    private BarRef instance;
+
+    public Builder() {
+      this(new BarRef());
+    }
+
+    protected Builder(BarRef instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(BarRef value) { 
+      super.copyOf(instance);
+      return this;
+    }
+
+    @Override
+    public BarRef.Builder name(String name) {
+      this.instance.name(name);
+      return this;
+    }
+    
+    @Override
+    public BarRef.Builder atReferredType(String atReferredType) {
+      this.instance.atReferredType(atReferredType);
+      return this;
+    }
+    
+    @Override
+    public BarRef.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public BarRef.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public BarRef.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public BarRef.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public BarRef.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built BarRef instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public BarRef build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static BarRef.Builder builder() {
+    return new BarRef.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public BarRef.Builder toBuilder() {
+    BarRef.Builder builder = new BarRef.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Entity.java

@@ -203,5 +203,87 @@ public class Entity {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder {
+
+    private Entity instance;
+
+    public Builder() {
+      this(new Entity());
+    }
+
+    protected Builder(Entity instance) {
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Entity value) { 
+      this.instance.setHref(value.href);
+      this.instance.setId(value.id);
+      this.instance.setAtSchemaLocation(value.atSchemaLocation);
+      this.instance.setAtBaseType(value.atBaseType);
+      this.instance.setAtType(value.atType);
+      return this;
+    }
+
+    public Entity.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    public Entity.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    public Entity.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    public Entity.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    public Entity.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built Entity instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Entity build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Entity.Builder builder() {
+    return new Entity.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Entity.Builder toBuilder() {
+    Entity.Builder builder = new Entity.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/EntityRef.java

@@ -248,5 +248,99 @@ public class EntityRef {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder {
+
+    private EntityRef instance;
+
+    public Builder() {
+      this(new EntityRef());
+    }
+
+    protected Builder(EntityRef instance) {
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(EntityRef value) { 
+      this.instance.setName(value.name);
+      this.instance.setAtReferredType(value.atReferredType);
+      this.instance.setHref(value.href);
+      this.instance.setId(value.id);
+      this.instance.setAtSchemaLocation(value.atSchemaLocation);
+      this.instance.setAtBaseType(value.atBaseType);
+      this.instance.setAtType(value.atType);
+      return this;
+    }
+
+    public EntityRef.Builder name(String name) {
+      this.instance.name(name);
+      return this;
+    }
+    
+    public EntityRef.Builder atReferredType(String atReferredType) {
+      this.instance.atReferredType(atReferredType);
+      return this;
+    }
+    
+    public EntityRef.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    public EntityRef.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    public EntityRef.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    public EntityRef.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    public EntityRef.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built EntityRef instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public EntityRef build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static EntityRef.Builder builder() {
+    return new EntityRef.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public EntityRef.Builder toBuilder() {
+    EntityRef.Builder builder = new EntityRef.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Extensible.java

@@ -138,5 +138,75 @@ public class Extensible {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder {
+
+    private Extensible instance;
+
+    public Builder() {
+      this(new Extensible());
+    }
+
+    protected Builder(Extensible instance) {
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Extensible value) { 
+      this.instance.setAtSchemaLocation(value.atSchemaLocation);
+      this.instance.setAtBaseType(value.atBaseType);
+      this.instance.setAtType(value.atType);
+      return this;
+    }
+
+    public Extensible.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    public Extensible.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    public Extensible.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built Extensible instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Extensible build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Extensible.Builder builder() {
+    return new Extensible.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Extensible.Builder toBuilder() {
+    Extensible.Builder builder = new Extensible.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Foo.java

@@ -146,5 +146,102 @@ public class Foo extends Entity implements FooRefOrValue {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends Entity.Builder {
+
+    private Foo instance;
+
+    public Builder() {
+      this(new Foo());
+    }
+
+    protected Builder(Foo instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Foo value) { 
+      super.copyOf(instance);
+      this.instance.setFooPropA(value.fooPropA);
+      this.instance.setFooPropB(value.fooPropB);
+      return this;
+    }
+
+    public Foo.Builder fooPropA(String fooPropA) {
+      this.instance.fooPropA(fooPropA);
+      return this;
+    }
+    
+    public Foo.Builder fooPropB(String fooPropB) {
+      this.instance.fooPropB(fooPropB);
+      return this;
+    }
+    
+    @Override
+    public Foo.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public Foo.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public Foo.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public Foo.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public Foo.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built Foo instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Foo build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Foo.Builder builder() {
+    return new Foo.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Foo.Builder toBuilder() {
+    Foo.Builder builder = new Foo.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/FooRef.java

@@ -132,5 +132,108 @@ public class FooRef extends EntityRef implements FooRefOrValue {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends EntityRef.Builder {
+
+    private FooRef instance;
+
+    public Builder() {
+      this(new FooRef());
+    }
+
+    protected Builder(FooRef instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(FooRef value) { 
+      super.copyOf(instance);
+      this.instance.setFoorefPropA(value.foorefPropA);
+      return this;
+    }
+
+    public FooRef.Builder foorefPropA(String foorefPropA) {
+      this.instance.foorefPropA(foorefPropA);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder name(String name) {
+      this.instance.name(name);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder atReferredType(String atReferredType) {
+      this.instance.atReferredType(atReferredType);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public FooRef.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built FooRef instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public FooRef build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static FooRef.Builder builder() {
+    return new FooRef.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public FooRef.Builder toBuilder() {
+    FooRef.Builder builder = new FooRef.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Pasta.java

@@ -122,5 +122,96 @@ public class Pasta extends Entity {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends Entity.Builder {
+
+    private Pasta instance;
+
+    public Builder() {
+      this(new Pasta());
+    }
+
+    protected Builder(Pasta instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Pasta value) { 
+      super.copyOf(instance);
+      this.instance.setVendor(value.vendor);
+      return this;
+    }
+
+    public Pasta.Builder vendor(String vendor) {
+      this.instance.vendor(vendor);
+      return this;
+    }
+    
+    @Override
+    public Pasta.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public Pasta.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public Pasta.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public Pasta.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public Pasta.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built Pasta instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Pasta build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Pasta.Builder builder() {
+    return new Pasta.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Pasta.Builder toBuilder() {
+    Pasta.Builder builder = new Pasta.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/Pizza.java

@@ -131,5 +131,96 @@ public class Pizza extends Entity {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends Entity.Builder {
+
+    private Pizza instance;
+
+    public Builder() {
+      this(new Pizza());
+    }
+
+    protected Builder(Pizza instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(Pizza value) { 
+      super.copyOf(instance);
+      this.instance.setPizzaSize(value.pizzaSize);
+      return this;
+    }
+
+    public Pizza.Builder pizzaSize(BigDecimal pizzaSize) {
+      this.instance.pizzaSize(pizzaSize);
+      return this;
+    }
+    
+    @Override
+    public Pizza.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public Pizza.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public Pizza.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public Pizza.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public Pizza.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built Pizza instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public Pizza build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static Pizza.Builder builder() {
+    return new Pizza.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public Pizza.Builder toBuilder() {
+    Pizza.Builder builder = new Pizza.Builder();
+    return builder.copyOf(this);
+  }
+
 }
 

samples/openapi3/server/petstore/spring-boot-oneof/src/main/java/org/openapitools/model/PizzaSpeziale.java

@@ -128,5 +128,102 @@ public class PizzaSpeziale extends Pizza {
     }
     return o.toString().replace("\n", "\n    ");
   }
+  
+  public static class Builder extends Pizza.Builder {
+
+    private PizzaSpeziale instance;
+
+    public Builder() {
+      this(new PizzaSpeziale());
+    }
+
+    protected Builder(PizzaSpeziale instance) {
+      super(instance); // the parent builder shares the same instance
+      this.instance = instance;
+    }
+
+    protected Builder copyOf(PizzaSpeziale value) { 
+      super.copyOf(instance);
+      this.instance.setToppings(value.toppings);
+      return this;
+    }
+
+    public PizzaSpeziale.Builder toppings(String toppings) {
+      this.instance.toppings(toppings);
+      return this;
+    }
+    
+    @Override
+    public PizzaSpeziale.Builder pizzaSize(BigDecimal pizzaSize) {
+      this.instance.pizzaSize(pizzaSize);
+      return this;
+    }
+    
+    @Override
+    public PizzaSpeziale.Builder href(String href) {
+      this.instance.href(href);
+      return this;
+    }
+    
+    @Override
+    public PizzaSpeziale.Builder id(String id) {
+      this.instance.id(id);
+      return this;
+    }
+    
+    @Override
+    public PizzaSpeziale.Builder atSchemaLocation(String atSchemaLocation) {
+      this.instance.atSchemaLocation(atSchemaLocation);
+      return this;
+    }
+    
+    @Override
+    public PizzaSpeziale.Builder atBaseType(String atBaseType) {
+      this.instance.atBaseType(atBaseType);
+      return this;
+    }
+    
+    @Override
+    public PizzaSpeziale.Builder atType(String atType) {
+      this.instance.atType(atType);
+      return this;
+    }
+    
+    /**
+    * returns a built PizzaSpeziale instance.
+    *
+    * The builder is not reusable (NullPointerException)
+    */
+    public PizzaSpeziale build() {
+      try {
+        return this.instance;
+      } finally {
+        // ensure that this.instance is not reused
+        super.build();
+        this.instance = null;
+      }
+    }
+
+    @Override
+    public String toString() {
+      return getClass() + "=(" + instance + ")";
+    }
+  }
+
+  /**
+  * Create a builder with no initialized field (except for the default values).
+  */
+  public static PizzaSpeziale.Builder builder() {
+    return new PizzaSpeziale.Builder();
+  }
+
+  /**
+  * Create a builder with a shallow copy of this instance.
+  */
+  public PizzaSpeziale.Builder toBuilder() {
+    PizzaSpeziale.Builder builder = new PizzaSpeziale.Builder();
+    return builder.copyOf(this);
+  }
+
 }