diff --git a/openapi/java.sh b/openapi/java.sh
index 2c695ef..4c7c479 100755
--- a/openapi/java.sh
+++ b/openapi/java.sh
@@ -49,7 +49,8 @@ popd > /dev/null
 source "${SCRIPT_ROOT}/openapi-generator/client-generator.sh"
 source "${SETTING_FILE}"
 
-OPENAPI_GENERATOR_COMMIT="${OPENAPI_GENERATOR_COMMIT:-v4.0.0}" \
+OPENAPI_GENERATOR_USER_ORG="${OPENAPI_GENERATOR_USER_ORG:-fabiokung}" \
+OPENAPI_GENERATOR_COMMIT="${OPENAPI_GENERATOR_COMMIT:-mapping-ref-string}" \
 CLIENT_LANGUAGE=java; \
 CLEANUP_DIRS=(docs src/test/java/io/kubernetes/client/apis src/main/java/io/kubernetes/client/apis src/main/java/io/kubernetes/client/models src/main/java/io/kubernetes/client/auth gradle); \
 kubeclient::generator::generate_client "${OUTPUT_DIR}"
diff --git a/openapi/java.xml b/openapi/java.xml
index 8cf26f7..d767367 100644
--- a/openapi/java.xml
+++ b/openapi/java.xml
@@ -46,9 +46,9 @@
                 <useRxJava>false</useRxJava>
                 <library>okhttp-gson</library>
                 <useReflectionEqualsHashCode>true</useReflectionEqualsHashCode>
-                <type-mappings>intstr.IntOrString=IntOrString,resource.Quantity=Quantity</type-mappings>
-                <import-mappings>IntOrString=io.kubernetes.client.custom.IntOrString,Quantity=io.kubernetes.client.custom.Quantity</import-mappings>
               </configOptions>
+              <typeMappings>int-or-string=IntOrString,quantity=Quantity</typeMappings>
+              <importMappings>IntOrString=io.kubernetes.client.custom.IntOrString,Quantity=io.kubernetes.client.custom.Quantity</importMappings>
               <output>${generator.output.path}</output>
             </configuration>
           </execution>
diff --git a/openapi/preprocess_spec.py b/openapi/preprocess_spec.py
index 14e8594..82b23b6 100644
--- a/openapi/preprocess_spec.py
+++ b/openapi/preprocess_spec.py
@@ -14,11 +14,11 @@
 
 from __future__ import print_function
 
+import argparse
 import json
 import operator
 import os.path
 import sys
-import argparse
 from collections import OrderedDict
 
 import urllib3
@@ -136,6 +136,8 @@ def process_swagger(spec, client_language):
 
     inline_primitive_models(spec, preserved_primitives_for_language(client_language))
 
+    add_custom_formatting(spec, format_for_language(client_language))
+
     remove_models(spec, removed_models_for_language(client_language))
 
     return spec
@@ -150,6 +152,12 @@ def preserved_primitives_for_language(client_language):
     else:
         return []
 
+def format_for_language(client_language):
+    if client_language == "java":
+        return {"resource.Quantity": "quantity"}
+    else:
+        return {}
+
 def removed_models_for_language(client_language):
     if client_language == "haskell-http-client":
         return ["intstr.IntOrString", "resource.Quantity"]
@@ -298,6 +306,12 @@ def inline_primitive_models(spec, excluded_primitives):
     for k in to_remove_models:
         del spec['definitions'][k]
 
+def add_custom_formatting(spec, custom_formats):
+    for k, v in spec['definitions'].items():
+        if k not in custom_formats:
+            continue
+        v["format"] = custom_formats[k]
+
 def write_json(filename, object):
     with open(filename, 'w') as out:
         json.dump(object, out, sort_keys=False, indent=2, separators=(',', ': '), ensure_ascii=True)