ImplBase for services not generated with spring boot 4.1.1.

Steps to reproduce:

1. generate a simple spring boot project with intellij idea:

plugins {
    java
    id("org.springframework.boot") version "4.1.1"  // works by changing this to 4.1.0
    id("io.spring.dependency-management") version "1.1.7"
    id("com.google.protobuf") version "0.9.6"
}

group = "com.example"
version = "0.0.1-SNAPSHOT"
description = "demo411"

java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(25)
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation("org.springframework.boot:spring-boot-starter-grpc-server")
    testImplementation("org.springframework.boot:spring-boot-starter-grpc-server-test")
    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
}

tasks.withType<Test> {
    useJUnitPlatform()
}

2. write a simple proto service

syntax = "proto3";

option java_multiple_files = true;
option java_package = "com.example.grpc_test.proto";
option java_outer_classname = "HelloWorldProto";

// The greeting service definition.
service Simple {
  // Sends a greeting
  rpc SayHello(HelloRequest) returns (HelloReply) {}
  rpc StreamHello(HelloRequest) returns (stream HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

3. the following code failed to compile becuase SimpleImplBase is not generated

import com.example.grpc_test.proto.SimpleGrpc;
class MyImpl extends SimpleGrpc.SimpleImplBase {

}

4. 4.1.1 left, 4.1.0 right

demo code

Environment info

I'm on macos aarch64, jdk is openjdk-25

Start with the Gradle configuration and the generated SimpleGrpc class in the linked demo project, comparing output from Spring Boot 4.1.1 and 4.1.0. Reproduce the compilation failure with MyImpl and identify why SimpleImplBase is absent in 4.1.1; done means the service base class is generated and the example compiles.