Fix open api specs for MULTI_SELECT (#8494)

## Before

![image](https://github.com/user-attachments/assets/b7384fb3-0f32-498b-99bb-27b8c15db00c)

## After

![image](https://github.com/user-attachments/assets/a8429849-559d-4494-8636-e5a6ddda7b47)

Author: martmull

packages/twenty-server/src/engine/core-modules/open-api/utils/__tests__/components.utils.spec.ts

@@ -125,8 +125,8 @@ describe('computeSchemaComponents', () => {
             enum: ['OPTION_1', 'OPTION_2'],
           },
           fieldMultiSelect: {
-            type: 'string',
-            enum: ['OPTION_1', 'OPTION_2'],
+            type: 'array',
+            items: { type: 'string', enum: ['OPTION_1', 'OPTION_2'] },
           },
           fieldPosition: {
             type: 'number',
@@ -302,8 +302,8 @@ describe('computeSchemaComponents', () => {
             enum: ['OPTION_1', 'OPTION_2'],
           },
           fieldMultiSelect: {
-            type: 'string',
-            enum: ['OPTION_1', 'OPTION_2'],
+            type: 'array',
+            items: { type: 'string', enum: ['OPTION_1', 'OPTION_2'] },
           },
           fieldPosition: {
             type: 'number',
@@ -478,8 +478,8 @@ describe('computeSchemaComponents', () => {
             enum: ['OPTION_1', 'OPTION_2'],
           },
           fieldMultiSelect: {
-            type: 'string',
-            enum: ['OPTION_1', 'OPTION_2'],
+            type: 'array',
+            items: { type: 'string', enum: ['OPTION_1', 'OPTION_2'] },
           },
           fieldPosition: {
             type: 'number',

packages/twenty-server/src/engine/core-modules/open-api/utils/components.utils.ts

@@ -115,8 +115,18 @@ const getSchemaComponentsProperties = ({
     let itemProperty = {} as Property;
 
     switch (field.type) {
-      case FieldMetadataType.SELECT:
       case FieldMetadataType.MULTI_SELECT:
+        itemProperty = {
+          type: 'array',
+          items: {
+            type: 'string',
+            enum: field.options.map(
+              (option: { value: string }) => option.value,
+            ),
+          },
+        };
+        break;
+      case FieldMetadataType.SELECT:
         itemProperty = {
           type: 'string',
           enum: field.options.map((option: { value: string }) => option.value),