diff --git a/modules/openapi-generator/src/main/resources/ocaml/model.mustache b/modules/openapi-generator/src/main/resources/ocaml/model.mustache
index 43518c27d96..161a2129d46 100644
--- a/modules/openapi-generator/src/main/resources/ocaml/model.mustache
+++ b/modules/openapi-generator/src/main/resources/ocaml/model.mustache
@@ -16,10 +16,31 @@ type t = {
     (* {{{.}}} *)
     {{/description}}
     {{#isEnum}}
-    {{{name}}}: {{^isMap}}Enums.{{/isMap}}{{{datatypeWithEnum}}}{{^isContainer}}{{#required}}{{#defaultValue}}[@default {{{.}}}]{{/defaultValue}}{{/required}}{{/isContainer}}{{^isContainer}}{{#required}}{{#isNullable}} option [@default {{#defaultValue}}Some({{{.}}}){{/defaultValue}}{{^defaultValue}}None{{/defaultValue}}]{{/isNullable}}{{/required}}{{/isContainer}}{{^isContainer}}{{^required}} option [@default {{#defaultValue}}Some({{{.}}}){{/defaultValue}}{{^defaultValue}}None{{/defaultValue}}]{{/required}}{{/isContainer}}; [@key "{{{baseName}}}"]
+      {{{name}}}: {{^isMap}}Enums.{{/isMap}}{{{datatypeWithEnum}}}
+        {{^isContainer}}
+          {{#required}}
+            {{#defaultValue}}[@default {{{.}}}]{{/defaultValue}}
+            {{#isNullable}} option [@default
+              {{#defaultValue}}Some({{{.}}}){{/defaultValue}}
+                {{^defaultValue}}None{{/defaultValue}}
+            ]
+            {{/isNullable}}
+          {{/required}}
+          {{^required}} option [@default
+            {{#defaultValue}}Some({{{.}}}){{/defaultValue}}
+            {{^defaultValue}}None{{/defaultValue}}
+          ]
+          {{/required}}
+        {{/isContainer}}; [@key "{{{baseName}}}"]
     {{/isEnum}}
     {{^isEnum}}
-    {{{name}}}: {{{datatypeWithEnum}}}{{^isContainer}}{{#required}}{{#isNullable}} option{{/isNullable}}{{/required}}{{/isContainer}}{{^isContainer}}{{^required}} option [@default None]{{/required}}{{/isContainer}}; [@key "{{{baseName}}}"]
+      {{{name}}}: {{{datatypeWithEnum}}}
+        {{^isContainer}}
+          {{#required}}{{#isNullable}} option{{/isNullable}}{{/required}}
+          {{^required}} option [@default None]{{/required}}
+        {{/isContainer}}
+        {{#isArray}}{{^required}} [@default []]{{/required}}{{/isArray}}
+        ; [@key "{{{baseName}}}"]
     {{/isEnum}}
 {{/vars}}
 } [@@deriving yojson { strict = false }, show ];;
diff --git a/samples/client/petstore/ocaml/src/models/api_response.ml b/samples/client/petstore/ocaml/src/models/api_response.ml
index c0e9f89438e..a656e6996a0 100644
--- a/samples/client/petstore/ocaml/src/models/api_response.ml
+++ b/samples/client/petstore/ocaml/src/models/api_response.ml
@@ -7,9 +7,21 @@
  *)
 
 type t = {
-    code: int32 option [@default None]; [@key "code"]
-    _type: string option [@default None]; [@key "type"]
-    message: string option [@default None]; [@key "message"]
+      code: int32
+          
+           option [@default None]
+        
+        ; [@key "code"]
+      _type: string
+          
+           option [@default None]
+        
+        ; [@key "type"]
+      message: string
+          
+           option [@default None]
+        
+        ; [@key "message"]
 } [@@deriving yojson { strict = false }, show ];;
 
 (** Describes the result of uploading an image resource *)
diff --git a/samples/client/petstore/ocaml/src/models/category.ml b/samples/client/petstore/ocaml/src/models/category.ml
index 6360bbbda49..c5edc5108e1 100644
--- a/samples/client/petstore/ocaml/src/models/category.ml
+++ b/samples/client/petstore/ocaml/src/models/category.ml
@@ -7,8 +7,16 @@
  *)
 
 type t = {
-    id: int64 option [@default None]; [@key "id"]
-    name: string option [@default None]; [@key "name"]
+      id: int64
+          
+           option [@default None]
+        
+        ; [@key "id"]
+      name: string
+          
+           option [@default None]
+        
+        ; [@key "name"]
 } [@@deriving yojson { strict = false }, show ];;
 
 (** A category for a pet *)
diff --git a/samples/client/petstore/ocaml/src/models/order.ml b/samples/client/petstore/ocaml/src/models/order.ml
index 594d69278d7..2849bc75a7e 100644
--- a/samples/client/petstore/ocaml/src/models/order.ml
+++ b/samples/client/petstore/ocaml/src/models/order.ml
@@ -7,13 +7,38 @@
  *)
 
 type t = {
-    id: int64 option [@default None]; [@key "id"]
-    pet_id: int64 option [@default None]; [@key "petId"]
-    quantity: int32 option [@default None]; [@key "quantity"]
-    ship_date: string option [@default None]; [@key "shipDate"]
+      id: int64
+          
+           option [@default None]
+        
+        ; [@key "id"]
+      pet_id: int64
+          
+           option [@default None]
+        
+        ; [@key "petId"]
+      quantity: int32
+          
+           option [@default None]
+        
+        ; [@key "quantity"]
+      ship_date: string
+          
+           option [@default None]
+        
+        ; [@key "shipDate"]
     (* Order Status *)
-    status: Enums.status option [@default None]; [@key "status"]
-    complete: bool option [@default None]; [@key "complete"]
+      status: Enums.status
+           option [@default
+            
+            None
+          ]
+        ; [@key "status"]
+      complete: bool
+          
+           option [@default None]
+        
+        ; [@key "complete"]
 } [@@deriving yojson { strict = false }, show ];;
 
 (** An order for a pets from the pet store *)
diff --git a/samples/client/petstore/ocaml/src/models/pet.ml b/samples/client/petstore/ocaml/src/models/pet.ml
index 34dcf0cd43c..fb3972dd65a 100644
--- a/samples/client/petstore/ocaml/src/models/pet.ml
+++ b/samples/client/petstore/ocaml/src/models/pet.ml
@@ -7,13 +7,34 @@
  *)
 
 type t = {
-    id: int64 option [@default None]; [@key "id"]
-    category: Category.t option [@default None]; [@key "category"]
-    name: string; [@key "name"]
-    photo_urls: string list; [@key "photoUrls"]
-    tags: Tag.t list; [@key "tags"]
+      id: int64
+          
+           option [@default None]
+        
+        ; [@key "id"]
+      category: Category.t
+          
+           option [@default None]
+        
+        ; [@key "category"]
+      name: string
+          
+          
+        
+        ; [@key "name"]
+      photo_urls: string list
+        
+        ; [@key "photoUrls"]
+      tags: Tag.t list
+         [@default []]
+        ; [@key "tags"]
     (* pet status in the store *)
-    status: Enums.pet_status option [@default None]; [@key "status"]
+      status: Enums.pet_status
+           option [@default
+            
+            None
+          ]
+        ; [@key "status"]
 } [@@deriving yojson { strict = false }, show ];;
 
 (** A pet for sale in the pet store *)
diff --git a/samples/client/petstore/ocaml/src/models/tag.ml b/samples/client/petstore/ocaml/src/models/tag.ml
index 36e5114e9af..349b43829fb 100644
--- a/samples/client/petstore/ocaml/src/models/tag.ml
+++ b/samples/client/petstore/ocaml/src/models/tag.ml
@@ -7,8 +7,16 @@
  *)
 
 type t = {
-    id: int64 option [@default None]; [@key "id"]
-    name: string option [@default None]; [@key "name"]
+      id: int64
+          
+           option [@default None]
+        
+        ; [@key "id"]
+      name: string
+          
+           option [@default None]
+        
+        ; [@key "name"]
 } [@@deriving yojson { strict = false }, show ];;
 
 (** A tag for a pet *)
diff --git a/samples/client/petstore/ocaml/src/models/user.ml b/samples/client/petstore/ocaml/src/models/user.ml
index 39a6be65f06..342089254b8 100644
--- a/samples/client/petstore/ocaml/src/models/user.ml
+++ b/samples/client/petstore/ocaml/src/models/user.ml
@@ -7,15 +7,47 @@
  *)
 
 type t = {
-    id: int64 option [@default None]; [@key "id"]
-    username: string option [@default None]; [@key "username"]
-    first_name: string option [@default None]; [@key "firstName"]
-    last_name: string option [@default None]; [@key "lastName"]
-    email: string option [@default None]; [@key "email"]
-    password: string option [@default None]; [@key "password"]
-    phone: string option [@default None]; [@key "phone"]
+      id: int64
+          
+           option [@default None]
+        
+        ; [@key "id"]
+      username: string
+          
+           option [@default None]
+        
+        ; [@key "username"]
+      first_name: string
+          
+           option [@default None]
+        
+        ; [@key "firstName"]
+      last_name: string
+          
+           option [@default None]
+        
+        ; [@key "lastName"]
+      email: string
+          
+           option [@default None]
+        
+        ; [@key "email"]
+      password: string
+          
+           option [@default None]
+        
+        ; [@key "password"]
+      phone: string
+          
+           option [@default None]
+        
+        ; [@key "phone"]
     (* User Status *)
-    user_status: int32 option [@default None]; [@key "userStatus"]
+      user_status: int32
+          
+           option [@default None]
+        
+        ; [@key "userStatus"]
 } [@@deriving yojson { strict = false }, show ];;
 
 (** A User who is purchasing from the pet store *)