X-Forwarded-Prefix not working when using MVC

[NilsEngelbach]

Describe the bug
When using Spring Cloud Gateway MVC (2023.0.1) with Spring Boot (3.2.4) the forwarded requests are missing the X-Forwarded-Prefix Header. I have prepared a small comparison. The only possibility I found was setting the Header manually using the AddRequestHeader=X-Forwarded-Prefix, /foo/bar filter.

Shared Configuration

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>2023.0.1</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>3.2.4</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        [...]
    </dependencies>

MVC Configuration

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway-mvc</artifactId>
        </dependency>

server:
  port: ${SERVER_PORT:8080}
  forward-headers-strategy: FRAMEWORK

spring:
  cloud:
    gateway:
      mvc:
        routes:
          - id: echo-service
            uri: <URL>
            filters:
              - StripPrefix=2
            predicates:
              - Path=/foo/bar/**

The forwarded Request ist missing the X-Forwarded-Prefix Header:

GET /baz HTTP/2.0

Host: <HOST>
X-Forwarded-For: 0:0:0:0:0:0:0:1
X-Forwarded-Host: localhost:8080
X-Forwarded-Port: 8080
X-Forwarded-Proto: http

REACTIVE Configuration

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>

server:
  port: ${SERVER_PORT:8080}
  forward-headers-strategy: FRAMEWORK

spring:
  cloud:
    gateway:
      routes:
        - id: echo-service
          uri: <URL>
          filters:
            - StripPrefix=2
          predicates:
            - Path=/foo/bar/**

GET /baz HTTP/1.1

Host: <HOST>
X-Forwarded-For: 0:0:0:0:0:0:0:1
X-Forwarded-Host: localhost:8080
X-Forwarded-Port: 8080
X-Forwarded-Prefix: /foo/bar
X-Forwarded-Proto: http