diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/ApiClient.mustache
index 732551cec585..854ac95cf915 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/ApiClient.mustache
@@ -197,7 +197,7 @@ public class ApiClient {
                 throw new IllegalArgumentException("OAuth2 token URL must be an absolute URL");
             }
         }
-        RetryingOAuth retryingOAuth = new RetryingOAuth(tokenUrl, clientId, OAuthFlow.{{flow}}, clientSecret, parameters);
+        RetryingOAuth retryingOAuth = new RetryingOAuth(tokenUrl, clientId, OAuthFlow.{{#lambda.uppercase}}{{#lambda.snakecase}}{{flow}}{{/lambda.snakecase}}{{/lambda.uppercase}}, clientSecret, parameters);
         authentications.put(
                 "{{name}}",
                 retryingOAuth
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/auth/RetryingOAuth.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/auth/RetryingOAuth.mustache
index 137e266b5a29..7b09aa700d61 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/auth/RetryingOAuth.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson-nextgen/auth/RetryingOAuth.mustache
@@ -65,16 +65,16 @@ public class RetryingOAuth extends OAuth implements Interceptor {
 
     public void setFlow(OAuthFlow flow) {
         switch(flow) {
-            case accessCode:
+            case ACCESS_CODE:
                 tokenRequestBuilder.setGrantType(GrantType.AUTHORIZATION_CODE);
                 break;
-            case implicit:
+            case IMPLICIT:
                 tokenRequestBuilder.setGrantType(GrantType.IMPLICIT);
                 break;
-            case password:
+            case PASSWORD:
                 tokenRequestBuilder.setGrantType(GrantType.PASSWORD);
                 break;
-            case application:
+            case APPLICATION:
                 tokenRequestBuilder.setGrantType(GrantType.CLIENT_CREDENTIALS);
                 break;
             default:
diff --git a/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/ApiClient.java
index 7e3cf65e18cf..a5fc2cca5d68 100644
--- a/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/ApiClient.java
@@ -180,7 +180,7 @@ public class ApiClient {
                 throw new IllegalArgumentException("OAuth2 token URL must be an absolute URL");
             }
         }
-        RetryingOAuth retryingOAuth = new RetryingOAuth(tokenUrl, clientId, OAuthFlow.implicit, clientSecret, parameters);
+        RetryingOAuth retryingOAuth = new RetryingOAuth(tokenUrl, clientId, OAuthFlow.IMPLICIT, clientSecret, parameters);
         authentications.put(
                 "petstore_auth",
                 retryingOAuth
diff --git a/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/auth/RetryingOAuth.java b/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/auth/RetryingOAuth.java
index 911df8d3a37d..a37cbdd5a55e 100644
--- a/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/auth/RetryingOAuth.java
+++ b/samples/client/petstore/java/okhttp-gson-nextgen/src/main/java/org/openapitools/client/auth/RetryingOAuth.java
@@ -64,16 +64,16 @@ public class RetryingOAuth extends OAuth implements Interceptor {
 
     public void setFlow(OAuthFlow flow) {
         switch(flow) {
-            case accessCode:
+            case ACCESS_CODE:
                 tokenRequestBuilder.setGrantType(GrantType.AUTHORIZATION_CODE);
                 break;
-            case implicit:
+            case IMPLICIT:
                 tokenRequestBuilder.setGrantType(GrantType.IMPLICIT);
                 break;
-            case password:
+            case PASSWORD:
                 tokenRequestBuilder.setGrantType(GrantType.PASSWORD);
                 break;
-            case application:
+            case APPLICATION:
                 tokenRequestBuilder.setGrantType(GrantType.CLIENT_CREDENTIALS);
                 break;
             default:
diff --git a/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/auth/RetryingOAuthTest.java b/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/auth/RetryingOAuthTest.java
index 7e0b2bec4b58..2d0d0743caf5 100644
--- a/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/auth/RetryingOAuthTest.java
+++ b/samples/client/petstore/java/okhttp-gson-nextgen/src/test/java/org/openapitools/client/auth/RetryingOAuthTest.java
@@ -36,7 +36,7 @@ public class RetryingOAuthTest {
                 new RetryingOAuth(
                         "_clientId",
                         "_clientSecret",
-                        OAuthFlow.accessCode,
+                        OAuthFlow.ACCESS_CODE,
                         "https://token.example.com",
                         Collections.<String, String>emptyMap());
         oauth.setAccessToken("expired-access-token");