Revert ServerServiceDefinition bean provider

In retrospect I think users should not have to create
ServerServiceDefinitions. It doesn't help anybody and
it seems like quite a deep internal detail.

Author: Dave Syer

spring-grpc-docs/src/main/antora/modules/ROOT/pages/server.adoc

@@ -7,13 +7,10 @@ The `Server` is the gRPC server that listens for incoming requests and routes th
 
 == Create a gRPC Service
 
-To create a gRPC server, you need to provide one or more beans of type `BindableService` or `ServerServiceDefinition`.
+To create a gRPC server, you need to provide one or more beans of type `BindableService`.
 There are some `BindableServices` available off the shelf that you could include in your application (an example is the reflection service from the `grpc-services` artifact which allows clients to browse the metadata of your services and download the Portobuf files). 
 Very commonly, you will create your own `BindableService` by extending the generated service implementation from your Protobuf file.
 The easiest way to activate it is to simply add a Spring `@Service` annotation to the implementation class and have it picked up by the `@ComponentScan` in your Spring Boot application.
-Alternatively, you could create an instance of it in a `@Configuration` class and return it as a bean, or return it's `ServerServiceDefinition`.
-The last option is useful if you need to add specific behaviour, like an interceptor, to the service.
-It is an error to have more than one instance of the same service name, so don't create both a `BindableService` and a `ServerServiceDefinition` bean for the same service.
 
 == Netty Server
 

spring-grpc-spring-boot-autoconfigure/src/main/java/org/springframework/grpc/autoconfigure/server/DefaultGrpcServiceDiscoverer.java

@@ -36,19 +36,14 @@ class DefaultGrpcServiceDiscoverer implements GrpcServiceDiscoverer {
 
 	private final ObjectProvider<BindableService> grpcServicesProvider;
 
-	private ObjectProvider<ServerServiceDefinition> grpcServiceDefinitionsProvider;
-
-	DefaultGrpcServiceDiscoverer(ObjectProvider<BindableService> grpcServicesProvider,
-			ObjectProvider<ServerServiceDefinition> grpcServiceDefinitionsProvider) {
+	DefaultGrpcServiceDiscoverer(ObjectProvider<BindableService> grpcServicesProvider) {
 		this.grpcServicesProvider = grpcServicesProvider;
-		this.grpcServiceDefinitionsProvider = grpcServiceDefinitionsProvider;
 	}
 
 	@Override
 	public List<ServerServiceDefinition> findServices() {
 		List<ServerServiceDefinition> list = new ArrayList<>(
 				grpcServicesProvider.orderedStream().map(BindableService::bindService).toList());
-		list.addAll(grpcServiceDefinitionsProvider.orderedStream().toList());
 		return list;
 	}
 

spring-grpc-spring-boot-autoconfigure/src/main/java/org/springframework/grpc/autoconfigure/server/GrpcServerAutoConfiguration.java

@@ -36,7 +36,6 @@
 import io.grpc.CompressorRegistry;
 import io.grpc.DecompressorRegistry;
 import io.grpc.ServerBuilder;
-import io.grpc.ServerServiceDefinition;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for gRPC server-side components.
@@ -76,9 +75,8 @@ ServerBuilderCustomizers serverBuilderCustomizers(ObjectProvider<ServerBuilderCu
 
 	@ConditionalOnMissingBean
 	@Bean
-	GrpcServiceDiscoverer grpcServiceDiscoverer(ObjectProvider<BindableService> bindableServicesProvider,
-			ObjectProvider<ServerServiceDefinition> serviceDefinitionsProvider) {
-		return new DefaultGrpcServiceDiscoverer(bindableServicesProvider, serviceDefinitionsProvider);
+	GrpcServiceDiscoverer grpcServiceDiscoverer(ObjectProvider<BindableService> bindableServicesProvider) {
+		return new DefaultGrpcServiceDiscoverer(bindableServicesProvider);
 	}
 
 	@ConditionalOnBean(CompressorRegistry.class)

spring-grpc-spring-boot-autoconfigure/src/test/java/org/springframework/grpc/autoconfigure/server/GrpcServerAutoConfigurationTests.java

@@ -134,17 +134,6 @@ void grpcServiceDiscovererAutoConfiguredAsExpected() {
 				.containsExactly(this.serviceDefinition));
 	}
 
-	@Test
-	void grpcServiceDiscovererWithServiceDefinitionAsExpected() {
-		ServerServiceDefinition serviceDefinition = ServerServiceDefinition.builder("my-other-service").build();
-		this.contextRunnerWithLifecyle()
-			.withBean(ServerServiceDefinition.class, () -> serviceDefinition)
-			.run((context) -> assertThat(context).getBean(GrpcServiceDiscoverer.class)
-				.extracting(GrpcServiceDiscoverer::findServices,
-						InstanceOfAssertFactories.list(ServerServiceDefinition.class))
-				.containsExactly(this.serviceDefinition, serviceDefinition));
-	}
-
 	@Test
 	void whenHasUserDefinedServerBuilderCustomizersDoesNotAutoConfigureBean() {
 		ServerBuilderCustomizers customCustomizers = mock(ServerBuilderCustomizers.class);