Correct relationship data requiredness in response models, so the generator doesn't need to overrule it

Author: bkoelman

src/JsonApiDotNetCore.OpenApi.Swashbuckle/JsonApiObjects/Relationships/NullableToOneRelationshipInResponse.cs

@@ -1,4 +1,3 @@
-using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
 using JetBrains.Annotations;
 using JsonApiDotNetCore.OpenApi.Swashbuckle.JsonApiObjects.Links;
@@ -15,7 +14,7 @@ internal sealed class NullableToOneRelationshipInResponse<TResource>
     [JsonPropertyName("links")]
     public RelationshipLinks Links { get; set; } = null!;
 
-    [Required]
+    // Non-required because related data may not be included in the response.
     [JsonPropertyName("data")]
     public ResourceIdentifierInResponse<TResource>? Data { get; set; }
 

src/JsonApiDotNetCore.OpenApi.Swashbuckle/JsonApiObjects/Relationships/ToManyRelationshipInResponse.cs

@@ -1,4 +1,3 @@
-using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
 using JetBrains.Annotations;
 using JsonApiDotNetCore.OpenApi.Swashbuckle.JsonApiObjects.Links;
@@ -15,7 +14,7 @@ internal sealed class ToManyRelationshipInResponse<TResource>
     [JsonPropertyName("links")]
     public RelationshipLinks Links { get; set; } = null!;
 
-    [Required]
+    // Non-required because related data may not be included in the response.
     [JsonPropertyName("data")]
     public ICollection<ResourceIdentifierInResponse<TResource>> Data { get; set; } = null!;
 

src/JsonApiDotNetCore.OpenApi.Swashbuckle/JsonApiObjects/Relationships/ToOneRelationshipInResponse.cs

@@ -1,4 +1,3 @@
-using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
 using JetBrains.Annotations;
 using JsonApiDotNetCore.OpenApi.Swashbuckle.JsonApiObjects.Links;
@@ -15,7 +14,7 @@ internal sealed class ToOneRelationshipInResponse<TResource>
     [JsonPropertyName("links")]
     public RelationshipLinks Links { get; set; } = null!;
 
-    [Required]
+    // Non-required because related data may not be included in the response.
     [JsonPropertyName("data")]
     public ResourceIdentifierInResponse<TResource> Data { get; set; } = null!;
 

src/JsonApiDotNetCore.OpenApi.Swashbuckle/SwaggerComponents/ResourceFieldSchemaBuilder.cs

@@ -207,8 +207,6 @@ private OpenApiSchema CreateReferenceSchemaForRelationship(Type relationshipSche
         if (JsonApiSchemaFacts.IsRelationshipInResponseType(relationshipSchemaType))
         {
             _linksVisibilitySchemaGenerator.UpdateSchemaForRelationship(relationshipSchemaType, fullSchema, schemaRepository);
-
-            fullSchema.Required.Remove(JsonApiPropertyName.Data);
         }
 
         return referenceSchema;