fix: missing deserialization for header content property in 3.1 and 3.0

src/Microsoft.OpenApi/Reader/V3/OpenApiHeaderDeserializer.cs

@@ -87,6 +87,12 @@ internal static partial class OpenApiV3Deserializer
                 "schema",
                 (o, n, t) => o.Schema = LoadSchema(n, t)
             },
+            {
+                "content", (o, n, t) =>
+                {
+                    o.Content = n.CreateMap(LoadMediaType, t);
+                }
+            },
             {
                 "examples",
                 (o, n, t) => o.Examples = n.CreateMap(LoadExample, t)

src/Microsoft.OpenApi/Reader/V31/OpenApiHeaderDeserializer.cs

@@ -87,6 +87,12 @@ internal static partial class OpenApiV31Deserializer
                     o.Schema = LoadSchema(n, t);
                 }
             },
+            {
+                "content", (o, n, t) =>
+                {
+                    o.Content = n.CreateMap(LoadMediaType, t);
+                }
+            },
             {
                 "examples", (o, n, t) =>
                 {

test/Microsoft.OpenApi.Readers.Tests/V31Tests/OpenApiHeaderTests.cs

@@ -0,0 +1,136 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.OpenApi.Reader;
+using Xunit;
+
+namespace Microsoft.OpenApi.Readers.Tests.V31Tests
+{
+    [Collection("DefaultSettings")]
+    public class OpenApiHeaderTests
+    {
+        private const string SampleFolderPath = "V31Tests/Samples/OpenApiHeader/";
+
+        [Fact]
+        public async Task ParseBasicHeaderShouldSucceed()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "basicHeader.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_1, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            Assert.Equivalent(
+                new OpenApiHeader
+                {
+                    Description = "The number of allowed requests in the current period",
+                    Schema = new OpenApiSchema()
+                    {
+                        Type = JsonSchemaType.Integer
+                    }
+                }, header);
+        }
+
+        [Fact]
+        public async Task ParseHeaderWithContentShouldSucceed()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "headerWithContent.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_1, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            Assert.Equivalent(
+                new OpenApiHeader
+                {
+                    Description = "A complex header with content",
+                    Content = new Dictionary<string, OpenApiMediaType>()
+                    {
+                        ["application/json"] = new()
+                        {
+                           Schema = new OpenApiSchema()
+                           {
+                                Type = JsonSchemaType.Object,
+                                Properties = new Dictionary<string, IOpenApiSchema>()
+                                {
+                                    ["timestamp"] = new OpenApiSchema()
+                                    {
+                                        Type = JsonSchemaType.String,
+                                        Format = "date-time"
+                                    },
+                                    ["value"] = new OpenApiSchema()
+                                    {
+                                        Type = JsonSchemaType.Integer
+                                    }
+                                }
+                           }
+                        }
+                    }
+                }, header);
+        }
+
+        [Fact]
+        public async Task ParseHeaderWithMultipleContentTypesShouldSucceed()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "headerWithMultipleContentTypes.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_1, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            Assert.Equivalent(
+                new OpenApiHeader
+                {
+                    Description = "A header that accepts multiple content types",
+                    Content = new Dictionary<string, OpenApiMediaType>()
+                    {
+                        ["application/json"] = new()
+                        {
+                           Schema = new OpenApiSchema()
+                           {
+                                Type = JsonSchemaType.Object,
+                                Properties = new Dictionary<string, IOpenApiSchema>()
+                                {
+                                    ["data"] = new OpenApiSchema()
+                                    {
+                                        Type = JsonSchemaType.String
+                                    }
+                                }
+                           }
+                        },
+                        ["text/plain"] = new()
+                        {
+                           Schema = new OpenApiSchema()
+                           {
+                                Type = JsonSchemaType.String
+                           }
+                        }
+                    }
+                }, header);
+        }
+
+        [Fact]
+        public async Task ParseHeaderWithStyleAndContentShouldPreferContent()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "headerWithStyleAndContent.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_1, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            // Both content and style can be present, content takes precedence for serialization behavior
+            Assert.NotNull(header.Content);
+            Assert.Single(header.Content);
+            Assert.True(header.Content.ContainsKey("application/json"));
+            Assert.Equal(ParameterStyle.Simple, header.Style); // Style can still be present
+        }
+    }
+}

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiHeader/basicHeader.yaml

@@ -0,0 +1,3 @@
+description: "The number of allowed requests in the current period"
+schema:
+  type: integer

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiHeader/headerWithContent.yaml

@@ -0,0 +1,11 @@
+description: "A complex header with content"
+content:
+  application/json:
+    schema:
+      type: object
+      properties:
+        timestamp:
+          type: string
+          format: date-time
+        value:
+          type: integer

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiHeader/headerWithMultipleContentTypes.yaml

@@ -0,0 +1,11 @@
+description: "A header that accepts multiple content types"
+content:
+  application/json:
+    schema:
+      type: object
+      properties:
+        data:
+          type: string
+  text/plain:
+    schema:
+      type: string

test/Microsoft.OpenApi.Readers.Tests/V31Tests/Samples/OpenApiHeader/headerWithStyleAndContent.yaml

@@ -0,0 +1,11 @@
+description: "A header with both style and content (content should take precedence)"
+style: simple
+schema:
+  type: string
+content:
+  application/json:
+    schema:
+      type: object
+      properties:
+        value:
+          type: string

test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiHeaderTests.cs

@@ -0,0 +1,136 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Microsoft.OpenApi.Reader;
+using Xunit;
+
+namespace Microsoft.OpenApi.Readers.Tests.V3Tests
+{
+    [Collection("DefaultSettings")]
+    public class OpenApiHeaderTests
+    {
+        private const string SampleFolderPath = "V3Tests/Samples/OpenApiHeader/";
+
+        [Fact]
+        public async Task ParseBasicHeaderShouldSucceed()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "basicHeader.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_0, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            Assert.Equivalent(
+                new OpenApiHeader
+                {
+                    Description = "The number of allowed requests in the current period",
+                    Schema = new OpenApiSchema()
+                    {
+                        Type = JsonSchemaType.Integer
+                    }
+                }, header);
+        }
+
+        [Fact]
+        public async Task ParseHeaderWithContentShouldSucceed()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "headerWithContent.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_0, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            Assert.Equivalent(
+                new OpenApiHeader
+                {
+                    Description = "A complex header with content",
+                    Content = new Dictionary<string, OpenApiMediaType>()
+                    {
+                        ["application/json"] = new()
+                        {
+                           Schema = new OpenApiSchema()
+                           {
+                                Type = JsonSchemaType.Object,
+                                Properties = new Dictionary<string, IOpenApiSchema>()
+                                {
+                                    ["timestamp"] = new OpenApiSchema()
+                                    {
+                                        Type = JsonSchemaType.String,
+                                        Format = "date-time"
+                                    },
+                                    ["value"] = new OpenApiSchema()
+                                    {
+                                        Type = JsonSchemaType.Integer
+                                    }
+                                }
+                           }
+                        }
+                    }
+                }, header);
+        }
+
+        [Fact]
+        public async Task ParseHeaderWithMultipleContentTypesShouldSucceed()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "headerWithMultipleContentTypes.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_0, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            Assert.Equivalent(
+                new OpenApiHeader
+                {
+                    Description = "A header that accepts multiple content types",
+                    Content = new Dictionary<string, OpenApiMediaType>()
+                    {
+                        ["application/json"] = new()
+                        {
+                           Schema = new OpenApiSchema()
+                           {
+                                Type = JsonSchemaType.Object,
+                                Properties = new Dictionary<string, IOpenApiSchema>()
+                                {
+                                    ["data"] = new OpenApiSchema()
+                                    {
+                                        Type = JsonSchemaType.String
+                                    }
+                                }
+                           }
+                        },
+                        ["text/plain"] = new()
+                        {
+                           Schema = new OpenApiSchema()
+                           {
+                                Type = JsonSchemaType.String
+                           }
+                        }
+                    }
+                }, header);
+        }
+
+        [Fact]
+        public async Task ParseHeaderWithStyleAndContentShouldPreferContent()
+        {
+            // Arrange
+            using var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "headerWithStyleAndContent.yaml"));
+
+            // Act
+            var header = await OpenApiModelFactory.LoadAsync<OpenApiHeader>(stream, OpenApiSpecVersion.OpenApi3_0, new(), settings: SettingsFixture.ReaderSettings);
+
+            // Assert
+            // Both content and style can be present, content takes precedence for serialization behavior
+            Assert.NotNull(header.Content);
+            Assert.Single(header.Content);
+            Assert.True(header.Content.ContainsKey("application/json"));
+            Assert.Equal(ParameterStyle.Simple, header.Style); // Style can still be present
+        }
+    }
+}

test/Microsoft.OpenApi.Readers.Tests/V3Tests/Samples/OpenApiHeader/basicHeader.yaml

@@ -0,0 +1,3 @@
+description: "The number of allowed requests in the current period"
+schema:
+  type: integer

test/Microsoft.OpenApi.Readers.Tests/V3Tests/Samples/OpenApiHeader/headerWithContent.yaml

@@ -0,0 +1,11 @@
+description: "A complex header with content"
+content:
+  application/json:
+    schema:
+      type: object
+      properties:
+        timestamp:
+          type: string
+          format: date-time
+        value:
+          type: integer

test/Microsoft.OpenApi.Readers.Tests/V3Tests/Samples/OpenApiHeader/headerWithMultipleContentTypes.yaml

@@ -0,0 +1,11 @@
+description: "A header that accepts multiple content types"
+content:
+  application/json:
+    schema:
+      type: object
+      properties:
+        data:
+          type: string
+  text/plain:
+    schema:
+      type: string

test/Microsoft.OpenApi.Readers.Tests/V3Tests/Samples/OpenApiHeader/headerWithStyleAndContent.yaml

@@ -0,0 +1,11 @@
+description: "A header with both style and content (content should take precedence)"
+style: simple
+schema:
+  type: string
+content:
+  application/json:
+    schema:
+      type: object
+      properties:
+        value:
+          type: string