diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java
index e09c32c96b2..0a44812ceac 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenModel.java
@@ -106,6 +106,7 @@ public class CodegenModel implements IJsonSchemaValidationProperties {
 
     public Map<String, Object> vendorExtensions = new HashMap<String, Object>();
     private CodegenComposedSchemas composedSchemas;
+    private boolean hasMultipleTypes = false;
 
     /**
      * The type of the value for the additionalProperties keyword in the OAS document.
@@ -816,6 +817,12 @@ public class CodegenModel implements IJsonSchemaValidationProperties {
         return composedSchemas;
     }
 
+    @Override
+    public boolean getHasMultipleTypes() {return hasMultipleTypes; }
+
+    @Override
+    public void setHasMultipleTypes(boolean hasMultipleTypes) { this.hasMultipleTypes = hasMultipleTypes; }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -849,6 +856,7 @@ public class CodegenModel implements IJsonSchemaValidationProperties {
                 hasOnlyReadOnly == that.hasOnlyReadOnly &&
                 isNull == that.isNull &&
                 hasValidation == that.hasValidation &&
+                hasMultipleTypes == that.getHasMultipleTypes() &&
                 hasDiscriminatorWithNonEmptyMapping == that.getHasDiscriminatorWithNonEmptyMapping() &&
                 getIsAnyType() == that.getIsAnyType() &&
                 getAdditionalPropertiesIsAnyType() == that.getAdditionalPropertiesIsAnyType() &&
@@ -926,7 +934,7 @@ public class CodegenModel implements IJsonSchemaValidationProperties {
                 getMinItems(), getMaxLength(), getMinLength(), getExclusiveMinimum(), getExclusiveMaximum(), getMinimum(),
                 getMaximum(), getPattern(), getMultipleOf(), getItems(), getAdditionalProperties(), getIsModel(),
                 getAdditionalPropertiesIsAnyType(), hasDiscriminatorWithNonEmptyMapping,
-                isAnyType, getComposedSchemas());
+                isAnyType, getComposedSchemas(), hasMultipleTypes);
     }
 
     @Override
@@ -1019,6 +1027,7 @@ public class CodegenModel implements IJsonSchemaValidationProperties {
         sb.append(", getHasDiscriminatorWithNonEmptyMapping=").append(hasDiscriminatorWithNonEmptyMapping);
         sb.append(", getIsAnyType=").append(getIsAnyType());
         sb.append(", composedSchemas=").append(composedSchemas);
+        sb.append(", hasMultipleTypes=").append(hasMultipleTypes);
         sb.append('}');
         return sb.toString();
     }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenParameter.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenParameter.java
index e0f962215df..38eb785410e 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenParameter.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenParameter.java
@@ -108,6 +108,7 @@ public class CodegenParameter implements IJsonSchemaValidationProperties {
     private boolean hasRequired;
     private boolean hasDiscriminatorWithNonEmptyMapping;
     private CodegenComposedSchemas composedSchemas;
+    private boolean hasMultipleTypes = false;
 
     public CodegenParameter copy() {
         CodegenParameter output = new CodegenParameter();
@@ -159,6 +160,7 @@ public class CodegenParameter implements IJsonSchemaValidationProperties {
         output.setHasVars(this.hasVars);
         output.setHasRequired(this.hasRequired);
         output.setHasDiscriminatorWithNonEmptyMapping(this.hasDiscriminatorWithNonEmptyMapping);
+        output.setHasMultipleTypes(this.hasMultipleTypes);
 
         if (this.composedSchemas != null) {
             output.setComposedSchemas(this.getComposedSchemas());
@@ -220,7 +222,7 @@ public class CodegenParameter implements IJsonSchemaValidationProperties {
 
     @Override
     public int hashCode() {
-        return Objects.hash(isFormParam, isQueryParam, isPathParam, isHeaderParam, isCookieParam, isBodyParam, isContainer, isCollectionFormatMulti, isPrimitiveType, isModel, isExplode, baseName, paramName, dataType, datatypeWithEnum, dataFormat, collectionFormat, description, unescapedDescription, baseType, defaultValue, enumName, style, isDeepObject, isAllowEmptyValue, example, jsonSchema, isString, isNumeric, isInteger, isLong, isNumber, isFloat, isDouble, isDecimal, isByteArray, isBinary, isBoolean, isDate, isDateTime, isUuid, isUri, isEmail, isFreeFormObject, isAnyType, isArray, isMap, isFile, isEnum, _enum, allowableValues, items, mostInnerItems, additionalProperties, vars, requiredVars, vendorExtensions, hasValidation, getMaxProperties(), getMinProperties(), isNullable, isDeprecated, required, getMaximum(), getExclusiveMaximum(), getMinimum(), getExclusiveMinimum(), getMaxLength(), getMinLength(), getPattern(), getMaxItems(), getMinItems(), getUniqueItems(), contentType, multipleOf, isNull, additionalPropertiesIsAnyType, hasVars, hasRequired, isShort, isUnboundedInteger, hasDiscriminatorWithNonEmptyMapping, composedSchemas);
+        return Objects.hash(isFormParam, isQueryParam, isPathParam, isHeaderParam, isCookieParam, isBodyParam, isContainer, isCollectionFormatMulti, isPrimitiveType, isModel, isExplode, baseName, paramName, dataType, datatypeWithEnum, dataFormat, collectionFormat, description, unescapedDescription, baseType, defaultValue, enumName, style, isDeepObject, isAllowEmptyValue, example, jsonSchema, isString, isNumeric, isInteger, isLong, isNumber, isFloat, isDouble, isDecimal, isByteArray, isBinary, isBoolean, isDate, isDateTime, isUuid, isUri, isEmail, isFreeFormObject, isAnyType, isArray, isMap, isFile, isEnum, _enum, allowableValues, items, mostInnerItems, additionalProperties, vars, requiredVars, vendorExtensions, hasValidation, getMaxProperties(), getMinProperties(), isNullable, isDeprecated, required, getMaximum(), getExclusiveMaximum(), getMinimum(), getExclusiveMinimum(), getMaxLength(), getMinLength(), getPattern(), getMaxItems(), getMinItems(), getUniqueItems(), contentType, multipleOf, isNull, additionalPropertiesIsAnyType, hasVars, hasRequired, isShort, isUnboundedInteger, hasDiscriminatorWithNonEmptyMapping, composedSchemas, hasMultipleTypes);
     }
 
     @Override
@@ -268,8 +270,9 @@ public class CodegenParameter implements IJsonSchemaValidationProperties {
                 isDeprecated == that.isDeprecated &&
                 required == that.required &&
                 isNull == that.isNull &&
-                hasDiscriminatorWithNonEmptyMapping && that.getHasDiscriminatorWithNonEmptyMapping() &&
+                hasDiscriminatorWithNonEmptyMapping == that.getHasDiscriminatorWithNonEmptyMapping() &&
                 getAdditionalPropertiesIsAnyType() == that.getAdditionalPropertiesIsAnyType() &&
+                hasMultipleTypes == that.getHasMultipleTypes() &&
                 getHasVars() == that.getHasVars() &&
                 getHasRequired() == that.getHasRequired() &&
                 getExclusiveMaximum() == that.getExclusiveMaximum() &&
@@ -399,6 +402,7 @@ public class CodegenParameter implements IJsonSchemaValidationProperties {
         sb.append(", getHasRequired=").append(hasRequired);
         sb.append(", getHasDiscriminatorWithNonEmptyMapping=").append(hasDiscriminatorWithNonEmptyMapping);
         sb.append(", composedSchemas=").append(composedSchemas);
+        sb.append(", hasMultipleTypes=").append(hasMultipleTypes);
         sb.append('}');
         return sb.toString();
     }
@@ -722,5 +726,11 @@ public class CodegenParameter implements IJsonSchemaValidationProperties {
     public CodegenComposedSchemas getComposedSchemas() {
         return composedSchemas;
     }
+
+    @Override
+    public boolean getHasMultipleTypes() {return hasMultipleTypes; }
+
+    @Override
+    public void setHasMultipleTypes(boolean hasMultipleTypes) { this.hasMultipleTypes = hasMultipleTypes; }
 }
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenProperty.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenProperty.java
index e326a052fca..c7a22915dbf 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenProperty.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenProperty.java
@@ -192,6 +192,7 @@ public class CodegenProperty implements Cloneable, IJsonSchemaValidationProperti
     private boolean hasRequired;
     private boolean hasDiscriminatorWithNonEmptyMapping;
     private CodegenComposedSchemas composedSchemas = null;
+    private boolean hasMultipleTypes = false;
 
     public String getBaseName() {
         return baseName;
@@ -801,6 +802,12 @@ public class CodegenProperty implements Cloneable, IJsonSchemaValidationProperti
         this.isAnyType = isAnyType;
     }
 
+    @Override
+    public boolean getHasMultipleTypes() {return hasMultipleTypes; }
+
+    @Override
+    public void setHasMultipleTypes(boolean hasMultipleTypes) { this.hasMultipleTypes = hasMultipleTypes; }
+
     @Override
     public String toString() {
         final StringBuilder sb = new StringBuilder("CodegenProperty{");
@@ -897,6 +904,7 @@ public class CodegenProperty implements Cloneable, IJsonSchemaValidationProperti
         sb.append(", getHasRequired=").append(getHasRequired());
         sb.append(", getHasDiscriminatorWithNonEmptyMapping=").append(hasDiscriminatorWithNonEmptyMapping);
         sb.append(", composedSchemas=").append(composedSchemas);
+        sb.append(", hasMultipleTypes=").append(hasMultipleTypes);
         sb.append('}');
         return sb.toString();
     }
@@ -948,6 +956,7 @@ public class CodegenProperty implements Cloneable, IJsonSchemaValidationProperti
                 isXmlAttribute == that.isXmlAttribute &&
                 isXmlWrapped == that.isXmlWrapped &&
                 isNull == that.isNull &&
+                hasMultipleTypes == that.getHasMultipleTypes() &&
                 hasDiscriminatorWithNonEmptyMapping == that.hasDiscriminatorWithNonEmptyMapping &&
                 getAdditionalPropertiesIsAnyType() == that.getAdditionalPropertiesIsAnyType() &&
                 getHasVars() == that.getHasVars() &&
@@ -1015,6 +1024,6 @@ public class CodegenProperty implements Cloneable, IJsonSchemaValidationProperti
                 vendorExtensions, hasValidation, isInherited, discriminatorValue, nameInCamelCase,
                 nameInSnakeCase, enumName, maxItems, minItems, isXmlAttribute, xmlPrefix, xmlName,
                 xmlNamespace, isXmlWrapped, isNull, additionalPropertiesIsAnyType, hasVars, hasRequired,
-                hasDiscriminatorWithNonEmptyMapping, composedSchemas);
+                hasDiscriminatorWithNonEmptyMapping, composedSchemas, hasMultipleTypes);
     }
 }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenResponse.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenResponse.java
index 545628931c7..b81bda5f583 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenResponse.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenResponse.java
@@ -86,6 +86,7 @@ public class CodegenResponse implements IJsonSchemaValidationProperties {
     private boolean hasRequired;
     private boolean hasDiscriminatorWithNonEmptyMapping;
     private CodegenComposedSchemas composedSchemas;
+    private boolean hasMultipleTypes = false;
 
     @Override
     public int hashCode() {
@@ -97,7 +98,7 @@ public class CodegenResponse implements IJsonSchemaValidationProperties {
                 getMaxProperties(), getMinProperties(), uniqueItems, getMaxItems(), getMinItems(), getMaxLength(),
                 getMinLength(), exclusiveMinimum, exclusiveMaximum, getMinimum(), getMaximum(), getPattern(),
                 is1xx, is2xx, is3xx, is4xx, is5xx, additionalPropertiesIsAnyType, hasVars, hasRequired,
-                hasDiscriminatorWithNonEmptyMapping, composedSchemas);
+                hasDiscriminatorWithNonEmptyMapping, composedSchemas, hasMultipleTypes);
     }
 
     @Override
@@ -142,6 +143,7 @@ public class CodegenResponse implements IJsonSchemaValidationProperties {
                 is4xx == that.is4xx &&
                 is5xx == that.is5xx &&
                 hasDiscriminatorWithNonEmptyMapping == that.getHasDiscriminatorWithNonEmptyMapping() &&
+                hasMultipleTypes == that.getHasMultipleTypes() &&
                 getAdditionalPropertiesIsAnyType() == that.getAdditionalPropertiesIsAnyType() &&
                 getHasVars() == that.getHasVars() &&
                 getHasRequired() == that.getHasRequired() &&
@@ -485,6 +487,7 @@ public class CodegenResponse implements IJsonSchemaValidationProperties {
         sb.append(", getHasRequired=").append(hasRequired);
         sb.append(", getHasDiscriminatorWithNonEmptyMapping=").append(hasDiscriminatorWithNonEmptyMapping);
         sb.append(", composedSchemas=").append(composedSchemas);
+        sb.append(", hasMultipleTypes=").append(hasMultipleTypes);
         sb.append('}');
         return sb.toString();
     }
@@ -583,4 +586,10 @@ public class CodegenResponse implements IJsonSchemaValidationProperties {
     public CodegenComposedSchemas getComposedSchemas() {
         return composedSchemas;
     }
+
+    @Override
+    public boolean getHasMultipleTypes() {return hasMultipleTypes; }
+
+    @Override
+    public void setHasMultipleTypes(boolean hasMultipleTypes) { this.hasMultipleTypes = hasMultipleTypes; }
 }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/IJsonSchemaValidationProperties.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/IJsonSchemaValidationProperties.java
index fe80c549ac6..eb95821d6f3 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/IJsonSchemaValidationProperties.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/IJsonSchemaValidationProperties.java
@@ -149,6 +149,9 @@ public interface IJsonSchemaValidationProperties {
 
     void setComposedSchemas(CodegenComposedSchemas composedSchemas);
 
+    boolean getHasMultipleTypes();
+
+    void setHasMultipleTypes(boolean hasMultipleTypes);
 
     /**
      * Syncs all the schema's type properties into the IJsonSchemaValidationProperties instance
diff --git a/samples/server/petstore/java-undertow/src/main/java/org/openapitools/handler/PathHandlerInterface.java b/samples/server/petstore/java-undertow/src/main/java/org/openapitools/handler/PathHandlerInterface.java
index 70d25fdaee1..3f538dd91f3 100644
--- a/samples/server/petstore/java-undertow/src/main/java/org/openapitools/handler/PathHandlerInterface.java
+++ b/samples/server/petstore/java-undertow/src/main/java/org/openapitools/handler/PathHandlerInterface.java
@@ -539,10 +539,10 @@ public interface PathHandlerInterface {
      * <p><b>Response headers</b>: [CodegenProperty{openApiType='integer', baseName='X-Rate-Limit', complexType='null', getter='getxRateLimit', setter='setxRateLimit', description='calls per hour allowed by the user', dataType='Integer', datatypeWithEnum='Integer', dataFormat='int32', name='xRateLimit', min='null', max='null', defaultValue='null', defaultValueWithParam=' = data.X-Rate-Limit;', baseType='Integer', containerType='null', title='null', unescapedDescription='calls per hour allowed by the user', maxLength=null, minLength=null, pattern='null', example='null', jsonSchema='{
   "type" : "integer",
   "format" : "int32"
-}', minimum='null', maximum='null', exclusiveMinimum=false, exclusiveMaximum=false, required=false, deprecated=false, hasMoreNonReadOnly=false, isPrimitiveType=true, isModel=false, isContainer=false, isString=false, isNumeric=true, isInteger=true, isShort=true, isLong=false, isUnboundedInteger=false, isNumber=false, isFloat=false, isDouble=false, isDecimal=false, isByteArray=false, isBinary=false, isFile=false, isBoolean=false, isDate=false, isDateTime=false, isUuid=false, isUri=false, isEmail=false, isFreeFormObject=false, isArray=false, isMap=false, isEnum=false, isReadOnly=false, isWriteOnly=false, isNullable=false, isSelfReference=false, isCircularReference=false, isDiscriminator=false, _enum=null, allowableValues=null, items=null, additionalProperties=null, vars=[], requiredVars=[], mostInnerItems=null, vendorExtensions={}, hasValidation=false, isInherited=false, discriminatorValue='null', nameInCamelCase='XRateLimit', nameInSnakeCase='X_RATE_LIMIT', enumName='null', maxItems=null, minItems=null, maxProperties=null, minProperties=null, uniqueItems=false, multipleOf=null, isXmlAttribute=false, xmlPrefix='null', xmlName='null', xmlNamespace='null', isXmlWrapped=false, isNull=false, getAdditionalPropertiesIsAnyType=false, getHasVars=false, getHasRequired=false, getHasDiscriminatorWithNonEmptyMapping=false, composedSchemas=null}, CodegenProperty{openApiType='string', baseName='X-Expires-After', complexType='Date', getter='getxExpiresAfter', setter='setxExpiresAfter', description='date in UTC when token expires', dataType='Date', datatypeWithEnum='Date', dataFormat='date-time', name='xExpiresAfter', min='null', max='null', defaultValue='null', defaultValueWithParam=' = data.X-Expires-After;', baseType='Date', containerType='null', title='null', unescapedDescription='date in UTC when token expires', maxLength=null, minLength=null, pattern='null', example='null', jsonSchema='{
+}', minimum='null', maximum='null', exclusiveMinimum=false, exclusiveMaximum=false, required=false, deprecated=false, hasMoreNonReadOnly=false, isPrimitiveType=true, isModel=false, isContainer=false, isString=false, isNumeric=true, isInteger=true, isShort=true, isLong=false, isUnboundedInteger=false, isNumber=false, isFloat=false, isDouble=false, isDecimal=false, isByteArray=false, isBinary=false, isFile=false, isBoolean=false, isDate=false, isDateTime=false, isUuid=false, isUri=false, isEmail=false, isFreeFormObject=false, isArray=false, isMap=false, isEnum=false, isReadOnly=false, isWriteOnly=false, isNullable=false, isSelfReference=false, isCircularReference=false, isDiscriminator=false, _enum=null, allowableValues=null, items=null, additionalProperties=null, vars=[], requiredVars=[], mostInnerItems=null, vendorExtensions={}, hasValidation=false, isInherited=false, discriminatorValue='null', nameInCamelCase='XRateLimit', nameInSnakeCase='X_RATE_LIMIT', enumName='null', maxItems=null, minItems=null, maxProperties=null, minProperties=null, uniqueItems=false, multipleOf=null, isXmlAttribute=false, xmlPrefix='null', xmlName='null', xmlNamespace='null', isXmlWrapped=false, isNull=false, getAdditionalPropertiesIsAnyType=false, getHasVars=false, getHasRequired=false, getHasDiscriminatorWithNonEmptyMapping=false, composedSchemas=null, hasMultipleTypes=false}, CodegenProperty{openApiType='string', baseName='X-Expires-After', complexType='Date', getter='getxExpiresAfter', setter='setxExpiresAfter', description='date in UTC when token expires', dataType='Date', datatypeWithEnum='Date', dataFormat='date-time', name='xExpiresAfter', min='null', max='null', defaultValue='null', defaultValueWithParam=' = data.X-Expires-After;', baseType='Date', containerType='null', title='null', unescapedDescription='date in UTC when token expires', maxLength=null, minLength=null, pattern='null', example='null', jsonSchema='{
   "type" : "string",
   "format" : "date-time"
-}', minimum='null', maximum='null', exclusiveMinimum=false, exclusiveMaximum=false, required=false, deprecated=false, hasMoreNonReadOnly=false, isPrimitiveType=false, isModel=false, isContainer=false, isString=false, isNumeric=false, isInteger=false, isShort=false, isLong=false, isUnboundedInteger=false, isNumber=false, isFloat=false, isDouble=false, isDecimal=false, isByteArray=false, isBinary=false, isFile=false, isBoolean=false, isDate=false, isDateTime=true, isUuid=false, isUri=false, isEmail=false, isFreeFormObject=false, isArray=false, isMap=false, isEnum=false, isReadOnly=false, isWriteOnly=false, isNullable=false, isSelfReference=false, isCircularReference=false, isDiscriminator=false, _enum=null, allowableValues=null, items=null, additionalProperties=null, vars=[], requiredVars=[], mostInnerItems=null, vendorExtensions={}, hasValidation=false, isInherited=false, discriminatorValue='null', nameInCamelCase='XExpiresAfter', nameInSnakeCase='X_EXPIRES_AFTER', enumName='null', maxItems=null, minItems=null, maxProperties=null, minProperties=null, uniqueItems=false, multipleOf=null, isXmlAttribute=false, xmlPrefix='null', xmlName='null', xmlNamespace='null', isXmlWrapped=false, isNull=false, getAdditionalPropertiesIsAnyType=false, getHasVars=false, getHasRequired=false, getHasDiscriminatorWithNonEmptyMapping=false, composedSchemas=null}]</p>
+}', minimum='null', maximum='null', exclusiveMinimum=false, exclusiveMaximum=false, required=false, deprecated=false, hasMoreNonReadOnly=false, isPrimitiveType=false, isModel=false, isContainer=false, isString=false, isNumeric=false, isInteger=false, isShort=false, isLong=false, isUnboundedInteger=false, isNumber=false, isFloat=false, isDouble=false, isDecimal=false, isByteArray=false, isBinary=false, isFile=false, isBoolean=false, isDate=false, isDateTime=true, isUuid=false, isUri=false, isEmail=false, isFreeFormObject=false, isArray=false, isMap=false, isEnum=false, isReadOnly=false, isWriteOnly=false, isNullable=false, isSelfReference=false, isCircularReference=false, isDiscriminator=false, _enum=null, allowableValues=null, items=null, additionalProperties=null, vars=[], requiredVars=[], mostInnerItems=null, vendorExtensions={}, hasValidation=false, isInherited=false, discriminatorValue='null', nameInCamelCase='XExpiresAfter', nameInSnakeCase='X_EXPIRES_AFTER', enumName='null', maxItems=null, minItems=null, maxProperties=null, minProperties=null, uniqueItems=false, multipleOf=null, isXmlAttribute=false, xmlPrefix='null', xmlName='null', xmlNamespace='null', isXmlWrapped=false, isNull=false, getAdditionalPropertiesIsAnyType=false, getHasVars=false, getHasRequired=false, getHasDiscriminatorWithNonEmptyMapping=false, composedSchemas=null, hasMultipleTypes=false}]</p>
      *
      * <p><b>Produces</b>: [{mediaType=application/xml}, {mediaType=application/json}]</p>
      * <p><b>Returns</b>: {@link String}</p>