Move Servlet HTTP Message Conversion to its own section

Closes gh-33063

framework-docs/modules/ROOT/nav.adoc

@@ -248,6 +248,7 @@
 **** xref:web/webmvc/mvc-servlet/multipart.adoc[]
 **** xref:web/webmvc/mvc-servlet/logging.adoc[]
 *** xref:web/webmvc/filters.adoc[]
+*** xref:web/webmvc/message-converters.adoc[]
 *** xref:web/webmvc/mvc-controller.adoc[]
 **** xref:web/webmvc/mvc-controller/ann.adoc[]
 **** xref:web/webmvc/mvc-controller/ann-requestmapping.adoc[]

framework-docs/modules/ROOT/pages/integration/rest-clients.adoc

@@ -366,68 +366,7 @@ val result = restClient.get()
 [[rest-message-conversion]]
 === HTTP Message Conversion
 
-[.small]#xref:web/webflux/reactive-spring.adoc#webflux-codecs[See equivalent in the Reactive stack]#
+xref:web/webmvc/message-converters.adoc#message-converters[See the supported HTTP message converters in the dedicated section].
-
-The `spring-web` module contains the `HttpMessageConverter` interface for reading and writing the body of HTTP requests and responses through `InputStream` and `OutputStream`.
-`HttpMessageConverter` instances are used on the client side (for example, in the `RestClient`) and on the server side (for example, in Spring MVC REST controllers).
-
-Concrete implementations for the main media (MIME) types are provided in the framework and are, by default, registered with the `RestClient` and `RestTemplate` on the client side and with `RequestMappingHandlerAdapter` on the server side (see xref:web/webmvc/mvc-config/message-converters.adoc[Configuring Message Converters]).
-
-Several implementations of `HttpMessageConverter` are described below.
-Refer to the {spring-framework-api}/http/converter/HttpMessageConverter.html[`HttpMessageConverter` Javadoc] for the complete list.
-For all converters, a default media type is used, but you can override it by setting the `supportedMediaTypes`  property.
-
-[[rest-message-converters-tbl]]
-.HttpMessageConverter Implementations
-[cols="1,3"]
-|===
-| MessageConverter | Description
-
-| `StringHttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write `String` instances from the HTTP request and response.
-By default, this converter supports all text media types(`text/{asterisk}`) and writes with a `Content-Type` of `text/plain`.
-
-| `FormHttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write form data from the HTTP request and response.
-By default, this converter reads and writes the `application/x-www-form-urlencoded` media type.
-Form data is read from and written into a `MultiValueMap<String, String>`.
-The converter can also write (but not read) multipart data read from a `MultiValueMap<String, Object>`.
-By default, `multipart/form-data` is supported.
-Additional multipart subtypes can be supported for writing form data.
-Consult the javadoc for `FormHttpMessageConverter` for further details.
-
-| `ByteArrayHttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write byte arrays from the HTTP request and response.
-By default, this converter supports all media types (`{asterisk}/{asterisk}`) and writes with a `Content-Type` of `application/octet-stream`.
-You can override this by setting the `supportedMediaTypes` property and overriding `getContentType(byte[])`.
-
-| `MarshallingHttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write XML by using Spring's `Marshaller` and `Unmarshaller` abstractions from the `org.springframework.oxm` package.
-This converter requires a `Marshaller` and `Unmarshaller` before it can be used.
-You can inject these through constructor or bean properties.
-By default, this converter supports `text/xml` and `application/xml`.
-
-| `MappingJackson2HttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write JSON by using Jackson's `ObjectMapper`.
-You can customize JSON mapping as needed through the use of Jackson's provided annotations.
-When you need further control (for cases where custom JSON serializers/deserializers need to be provided for specific types), you can inject a custom `ObjectMapper` through the `ObjectMapper` property.
-By default, this converter supports `application/json`.
-
-| `MappingJackson2XmlHttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write XML by using {jackson-github-org}/jackson-dataformat-xml[Jackson XML] extension's `XmlMapper`.
-You can customize XML mapping as needed through the use of JAXB or Jackson's provided annotations.
-When you need further control (for cases where custom XML serializers/deserializers need to be provided for specific types), you can inject a custom `XmlMapper` through the `ObjectMapper` property.
-By default, this converter supports `application/xml`.
-
-| `SourceHttpMessageConverter`
-| An `HttpMessageConverter` implementation that can read and write `javax.xml.transform.Source` from the HTTP request and response.
-Only `DOMSource`, `SAXSource`, and `StreamSource` are supported.
-By default, this converter supports `text/xml` and `application/xml`.
-
-|===
-
-By default, `RestClient` and `RestTemplate` register all built-in message converters, depending on the availability of underlying libraries on the classpath.
-You can also set the message converters to use explicitly, by using the `messageConverters()` method on the `RestClient` builder, or via the `messageConverters` property of `RestTemplate`.
 
 ==== Jackson JSON Views
 

framework-docs/modules/ROOT/pages/web/webflux/reactive-spring.adoc

@@ -453,7 +453,7 @@ The following table describes the available `WebExceptionHandler` implementation
 
 [[webflux-codecs]]
 == Codecs
-[.small]#xref:integration/rest-clients.adoc#rest-message-conversion[See equivalent in the Servlet stack]#
+[.small]#xref:web/webmvc/message-converters.adoc#message-converters[See equivalent in the Servlet stack]#
 
 The `spring-web` and `spring-core` modules provide support for serializing and
 deserializing byte content to and from higher level objects through non-blocking I/O with
@@ -562,6 +562,18 @@ for repeated, map-like access to parts, or otherwise rely on the
 `SynchronossPartHttpMessageReader` for a one-time access to `Flux<Part>`.
 
 
+[[webflux-codecs-protobuf]]
+=== Protocol Buffers
+
+`ProtobufEncoder` and `ProtobufDecoder` supporting decoding and encoding "application/x-protobuf", "application/octet-stream"
+and "application/vnd.google.protobuf" content for `com.google.protobuf.Message` types. They also support stream of values
+if content is received/sent with the "delimited" parameter along the content type (like "application/x-protobuf;delimited=true").
+This requires the "com.google.protobuf:protobuf-java" library, version 3.29 and higher.
+
+The `ProtobufJsonDecoder` and `ProtobufJsonEncoder` variants support reading and writing JSON documents to and from Protobuf messages.
+They require the "com.google.protobuf:protobuf-java-util" dependency. Note, the JSON variants do not support reading stream of messages,
+see the {spring-framework-api}/http/codec/protobuf/ProtobufJsonDecoder.html[javadoc of `ProtobufJsonDecoder`] for more details.
+
 [[webflux-codecs-limits]]
 === Limits
 

framework-docs/modules/ROOT/pages/web/webmvc/message-converters.adoc

@@ -0,0 +1,83 @@
+[[message-converters]]
+= HTTP Message Conversion
+
+[.small]#xref:web/webflux/reactive-spring.adoc#webflux-codecs[See equivalent in the Reactive stack]#
+
+The `spring-web` module contains the `HttpMessageConverter` interface for reading and writing the body of HTTP requests and responses through `InputStream` and `OutputStream`.
+`HttpMessageConverter` instances are used on the client side (for example, in the `RestClient`) and on the server side (for example, in Spring MVC REST controllers).
+
+Concrete implementations for the main media (MIME) types are provided in the framework and are, by default, registered with the `RestClient` and `RestTemplate` on the client side and with `RequestMappingHandlerAdapter` on the server side (see xref:web/webmvc/mvc-config/message-converters.adoc[Configuring Message Converters]).
+
+Several implementations of `HttpMessageConverter` are described below.
+Refer to the {spring-framework-api}/http/converter/HttpMessageConverter.html[`HttpMessageConverter` Javadoc] for the complete list.
+For all converters, a default media type is used, but you can override it by setting the `supportedMediaTypes`  property.
+
+[[rest-message-converters-tbl]]
+.HttpMessageConverter Implementations
+[cols="1,3"]
+|===
+| MessageConverter | Description
+
+| `StringHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write `String` instances from the HTTP request and response.
+By default, this converter supports all text media types(`text/{asterisk}`) and writes with a `Content-Type` of `text/plain`.
+
+| `FormHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write form data from the HTTP request and response.
+By default, this converter reads and writes the `application/x-www-form-urlencoded` media type.
+Form data is read from and written into a `MultiValueMap<String, String>`.
+The converter can also write (but not read) multipart data read from a `MultiValueMap<String, Object>`.
+By default, `multipart/form-data` is supported.
+Additional multipart subtypes can be supported for writing form data.
+Consult the javadoc for `FormHttpMessageConverter` for further details.
+
+| `ByteArrayHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write byte arrays from the HTTP request and response.
+By default, this converter supports all media types (`{asterisk}/{asterisk}`) and writes with a `Content-Type` of `application/octet-stream`.
+You can override this by setting the `supportedMediaTypes` property and overriding `getContentType(byte[])`.
+
+| `MarshallingHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write XML by using Spring's `Marshaller` and `Unmarshaller` abstractions from the `org.springframework.oxm` package.
+This converter requires a `Marshaller` and `Unmarshaller` before it can be used.
+You can inject these through constructor or bean properties.
+By default, this converter supports `text/xml` and `application/xml`.
+
+| `MappingJackson2HttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write JSON by using Jackson's `ObjectMapper`.
+You can customize JSON mapping as needed through the use of Jackson's provided annotations.
+When you need further control (for cases where custom JSON serializers/deserializers need to be provided for specific types), you can inject a custom `ObjectMapper` through the `ObjectMapper` property.
+By default, this converter supports `application/json`. This requires the `com.fasterxml.jackson.core:jackson-databind` dependency.
+
+| `MappingJackson2XmlHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write XML by using {jackson-github-org}/jackson-dataformat-xml[Jackson XML] extension's `XmlMapper`.
+You can customize XML mapping as needed through the use of JAXB or Jackson's provided annotations.
+When you need further control (for cases where custom XML serializers/deserializers need to be provided for specific types), you can inject a custom `XmlMapper` through the `ObjectMapper` property.
+By default, this converter supports `application/xml`. This requires the `com.fasterxml.jackson.dataformat:jackson-dataformat-xml` dependency.
+
+| `MappingJackson2CborHttpMessageConverter`
+| `com.fasterxml.jackson.dataformat:jackson-dataformat-cbor`
+
+| `SourceHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write `javax.xml.transform.Source` from the HTTP request and response.
+Only `DOMSource`, `SAXSource`, and `StreamSource` are supported.
+By default, this converter supports `text/xml` and `application/xml`.
+
+| `GsonHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write JSON by using "Google Gson".
+This requires the `com.google.code.gson:gson` dependency.
+
+| `JsonbHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write JSON by using the Jakarta Json Bind API.
+This requires the `jakarta.json.bind:jakarta.json.bind-api` dependency and an implementation available.
+
+| `ProtobufHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write Protobuf messages in binary format with the `"application/x-protobuf"`
+content type. This requires the `com.google.protobuf:protobuf-java` dependency.
+
+| `ProtobufJsonFormatHttpMessageConverter`
+| An `HttpMessageConverter` implementation that can read and write JSON documents to and from Protobuf messages.
+This requires the `com.google.protobuf:protobuf-java-util` dependency.
+
+|===
+
+