diff --git a/src/Altinn.App.Api/Models/DataPatchResponseMultiple.cs b/src/Altinn.App.Api/Models/DataPatchResponseMultiple.cs
index dcd2c41b9..8bf763b9a 100644
--- a/src/Altinn.App.Api/Models/DataPatchResponseMultiple.cs
+++ b/src/Altinn.App.Api/Models/DataPatchResponseMultiple.cs
@@ -1,3 +1,4 @@
+using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
 using Altinn.App.Api.Controllers;
 using Altinn.App.Core.Models.Validation;
@@ -13,19 +14,19 @@ public class DataPatchResponseMultiple
     /// <summary>
     /// The validation issues that were found during the patch operation.
     /// </summary>
-    [JsonPropertyName("validationIssues")]
+    [JsonPropertyName("validationIssues"), Required]
     public required List<ValidationSourcePair> ValidationIssues { get; init; }
 
     /// <summary>
     /// The current data in all data models updated by the patch operation.
     /// </summary>
-    [JsonPropertyName("newDataModels")]
+    [JsonPropertyName("newDataModels"), Required]
     public required List<DataModelPairResponse> NewDataModels { get; init; }
 
     /// <summary>
     /// The instance with updated dataElement list.
     /// </summary>
-    [JsonPropertyName("instance")]
+    [JsonPropertyName("instance"), Required]
     public required Instance Instance { get; init; }
 }
 
@@ -35,6 +36,6 @@ public class DataPatchResponseMultiple
 /// <param name="DataElementId">The guid of the DataElement</param>
 /// <param name="Data">The form data of the data element</param>
 public record DataModelPairResponse(
-    [property: JsonPropertyName("dataElementId")] Guid DataElementId,
-    [property: JsonPropertyName("data")] object Data
+    [property: JsonPropertyName("dataElementId"), Required] Guid DataElementId,
+    [property: JsonPropertyName("data"), Required] object Data
 );
diff --git a/src/Altinn.App.Api/Models/DataPostResponse.cs b/src/Altinn.App.Api/Models/DataPostResponse.cs
index 11a26145e..72948820c 100644
--- a/src/Altinn.App.Api/Models/DataPostResponse.cs
+++ b/src/Altinn.App.Api/Models/DataPostResponse.cs
@@ -1,3 +1,4 @@
+using System.ComponentModel.DataAnnotations;
 using System.Net;
 using System.Text.Json.Serialization;
 using Altinn.App.Core.Models.Validation;
@@ -14,25 +15,25 @@ public class DataPostResponse
     /// <summary>
     /// The Id of the created data element
     /// </summary>
-    [JsonPropertyName("newDataElementId")]
+    [JsonPropertyName("newDataElementId"), Required]
     public required Guid NewDataElementId { get; init; }
 
     /// <summary>
     /// The instance with updated data
     /// </summary>
-    [JsonPropertyName("instance")]
+    [JsonPropertyName("instance"), Required]
     public required Instance Instance { get; init; }
 
     /// <summary>
     /// List of validation issues that reported to have relevant changes after a new data element was added
     /// </summary>
-    [JsonPropertyName("validationIssues")]
+    [JsonPropertyName("validationIssues"), Required]
     public required List<ValidationSourcePair> ValidationIssues { get; init; }
 
     /// <summary>
     /// List of updated DataModels caused by dataProcessing
     /// </summary>
-    [JsonPropertyName("newDataModels")]
+    [JsonPropertyName("newDataModels"), Required]
     public required List<DataModelPairResponse> NewDataModels { get; init; }
 }
 
@@ -55,6 +56,6 @@ public DataPostErrorResponse(string detail, List<ValidationIssueWithSource> vali
     /// <summary>
     /// List of the validators that reported to have relevant changes after a new data element was added
     /// </summary>
-    [JsonPropertyName("uploadValidationIssues")]
+    [JsonPropertyName("uploadValidationIssues"), Required]
     public List<ValidationIssueWithSource> UploadValidationIssues { get; }
 }
diff --git a/src/Altinn.App.Core/Models/Validation/ValidationIssueWithSource.cs b/src/Altinn.App.Core/Models/Validation/ValidationIssueWithSource.cs
index 551c6ac27..8c54e6c7a 100644
--- a/src/Altinn.App.Core/Models/Validation/ValidationIssueWithSource.cs
+++ b/src/Altinn.App.Core/Models/Validation/ValidationIssueWithSource.cs
@@ -1,3 +1,4 @@
+using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
 using Altinn.App.Core.Features;
 
@@ -70,7 +71,7 @@ public static ValidationIssueWithSource FromIssue(ValidationIssue issue, string
     /// <summary>
     /// The short name of the class that crated the message (set automatically after return of list)
     /// </summary>
-    [JsonPropertyName("source")]
+    [JsonPropertyName("source"), Required]
     public required string Source { get; set; }
 
     /// <summary>
@@ -106,6 +107,6 @@ public static ValidationIssueWithSource FromIssue(ValidationIssue issue, string
 /// <param name="Source">The <see cref="IValidator.ValidationSource"/> for the Validator that created theese issues</param>
 /// <param name="Issues">List of issues</param>
 public record ValidationSourcePair(
-    [property: JsonPropertyName("source")] string Source,
-    [property: JsonPropertyName("issues")] List<ValidationIssueWithSource> Issues
+    [property: JsonPropertyName("source"), Required] string Source,
+    [property: JsonPropertyName("issues"), Required] List<ValidationIssueWithSource> Issues
 );
diff --git a/test/Altinn.App.Api.Tests/OpenApi/OpenApiSpecChangeDetection.SaveJsonSwagger.verified.txt b/test/Altinn.App.Api.Tests/OpenApi/OpenApiSpecChangeDetection.SaveJsonSwagger.verified.txt
index a49147298..14d3f68e0 100644
--- a/test/Altinn.App.Api.Tests/OpenApi/OpenApiSpecChangeDetection.SaveJsonSwagger.verified.txt
+++ b/test/Altinn.App.Api.Tests/OpenApi/OpenApiSpecChangeDetection.SaveJsonSwagger.verified.txt
@@ -1,4 +1,4 @@
-{
+{
   openapi: 3.0.1,
   info: {
     title: Altinn App Api,
@@ -6442,6 +6442,10 @@ to a model, and then finally the state of the instance.,
         additionalProperties: false
       },
       DataModelPairResponse: {
+        required: [
+          data,
+          dataElementId
+        ],
         type: object,
         properties: {
           dataElementId: {
@@ -6450,8 +6454,7 @@ to a model, and then finally the state of the instance.,
             format: uuid
           },
           data: {
-            description: The form data of the data element,
-            nullable: true
+            description: The form data of the data element
           }
         },
         additionalProperties: false,
@@ -6555,16 +6558,14 @@ version that supports multiple data models in the same request.
             items: {
               $ref: #/components/schemas/ValidationSourcePair
             },
-            description: The validation issues that were found during the patch operation.,
-            nullable: true
+            description: The validation issues that were found during the patch operation.
           },
           newDataModels: {
             type: array,
             items: {
               $ref: #/components/schemas/DataModelPairResponse
             },
-            description: The current data in all data models updated by the patch operation.,
-            nullable: true
+            description: The current data in all data models updated by the patch operation.
           },
           instance: {
             $ref: #/components/schemas/Instance
@@ -6574,6 +6575,9 @@ version that supports multiple data models in the same request.
         description: Represents the response from a data patch operation on the Altinn.App.Api.Controllers.DataController.
       },
       DataPostErrorResponse: {
+        required: [
+          uploadValidationIssues
+        ],
         type: object,
         properties: {
           type: {
@@ -6603,7 +6607,6 @@ version that supports multiple data models in the same request.
               $ref: #/components/schemas/ValidationIssueWithSource
             },
             description: List of the validators that reported to have relevant changes after a new data element was added,
-            nullable: true,
             readOnly: true
           }
         },
@@ -6631,16 +6634,14 @@ version that supports multiple data models in the same request.
             items: {
               $ref: #/components/schemas/ValidationSourcePair
             },
-            description: List of validation issues that reported to have relevant changes after a new data element was added,
-            nullable: true
+            description: List of validation issues that reported to have relevant changes after a new data element was added
           },
           newDataModels: {
             type: array,
             items: {
               $ref: #/components/schemas/DataModelPairResponse
             },
-            description: List of updated DataModels caused by dataProcessing,
-            nullable: true
+            description: List of updated DataModels caused by dataProcessing
           }
         },
         additionalProperties: false,
@@ -8147,8 +8148,8 @@ Validators that are not listed in the dictionary are assumed to have not been ex
             nullable: true
           },
           source: {
-            type: string,
-            nullable: true
+            minLength: 1,
+            type: string
           },
           noIncrementalUpdates: {
             type: boolean
@@ -8168,18 +8169,21 @@ Validators that are not listed in the dictionary are assumed to have not been ex
         additionalProperties: false
       },
       ValidationSourcePair: {
+        required: [
+          issues,
+          source
+        ],
         type: object,
         properties: {
           source: {
-            type: string,
-            nullable: true
+            minLength: 1,
+            type: string
           },
           issues: {
             type: array,
             items: {
               $ref: #/components/schemas/ValidationIssueWithSource
-            },
-            nullable: true
+            }
           }
         },
         additionalProperties: false
diff --git a/test/Altinn.App.Api.Tests/OpenApi/swagger.json b/test/Altinn.App.Api.Tests/OpenApi/swagger.json
index aa147604a..c52af90c8 100644
--- a/test/Altinn.App.Api.Tests/OpenApi/swagger.json
+++ b/test/Altinn.App.Api.Tests/OpenApi/swagger.json
@@ -6443,6 +6443,10 @@
         "additionalProperties": false
       },
       "DataModelPairResponse": {
+        "required": [
+          "data",
+          "dataElementId"
+        ],
         "type": "object",
         "properties": {
           "dataElementId": {
@@ -6451,8 +6455,7 @@
             "format": "uuid"
           },
           "data": {
-            "description": "The form data of the data element",
-            "nullable": true
+            "description": "The form data of the data element"
           }
         },
         "additionalProperties": false,
@@ -6550,16 +6553,14 @@
             "items": {
               "$ref": "#/components/schemas/ValidationSourcePair"
             },
-            "description": "The validation issues that were found during the patch operation.",
-            "nullable": true
+            "description": "The validation issues that were found during the patch operation."
           },
           "newDataModels": {
             "type": "array",
             "items": {
               "$ref": "#/components/schemas/DataModelPairResponse"
             },
-            "description": "The current data in all data models updated by the patch operation.",
-            "nullable": true
+            "description": "The current data in all data models updated by the patch operation."
           },
           "instance": {
             "$ref": "#/components/schemas/Instance"
@@ -6569,6 +6570,9 @@
         "description": "Represents the response from a data patch operation on the Altinn.App.Api.Controllers.DataController."
       },
       "DataPostErrorResponse": {
+        "required": [
+          "uploadValidationIssues"
+        ],
         "type": "object",
         "properties": {
           "type": {
@@ -6598,7 +6602,6 @@
               "$ref": "#/components/schemas/ValidationIssueWithSource"
             },
             "description": "List of the validators that reported to have relevant changes after a new data element was added",
-            "nullable": true,
             "readOnly": true
           }
         },
@@ -6627,16 +6630,14 @@
             "items": {
               "$ref": "#/components/schemas/ValidationSourcePair"
             },
-            "description": "List of validation issues that reported to have relevant changes after a new data element was added",
-            "nullable": true
+            "description": "List of validation issues that reported to have relevant changes after a new data element was added"
           },
           "newDataModels": {
             "type": "array",
             "items": {
               "$ref": "#/components/schemas/DataModelPairResponse"
             },
-            "description": "List of updated DataModels caused by dataProcessing",
-            "nullable": true
+            "description": "List of updated DataModels caused by dataProcessing"
           }
         },
         "additionalProperties": false,
@@ -8143,8 +8144,8 @@
             "nullable": true
           },
           "source": {
-            "type": "string",
-            "nullable": true
+            "minLength": 1,
+            "type": "string"
           },
           "noIncrementalUpdates": {
             "type": "boolean"
@@ -8164,18 +8165,21 @@
         "additionalProperties": false
       },
       "ValidationSourcePair": {
+        "required": [
+          "issues",
+          "source"
+        ],
         "type": "object",
         "properties": {
           "source": {
-            "type": "string",
-            "nullable": true
+            "minLength": 1,
+            "type": "string"
           },
           "issues": {
             "type": "array",
             "items": {
               "$ref": "#/components/schemas/ValidationIssueWithSource"
-            },
-            "nullable": true
+            }
           }
         },
         "additionalProperties": false