Skip gRPC port initializer when spring-grpc is absent

module/spring-boot-grpc-test/src/main/java/org/springframework/boot/grpc/test/autoconfigure/GrpcPortInfoApplicationContextInitializer.java

@@ -31,6 +31,7 @@
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertySource;
+import org.springframework.util.ClassUtils;
 import org.springframework.grpc.server.GrpcServerFactory;
 import org.springframework.grpc.server.InProcessGrpcServerFactory;
 import org.springframework.grpc.server.lifecycle.GrpcServerStartedEvent;
@@ -50,8 +51,13 @@
 class GrpcPortInfoApplicationContextInitializer
 		implements ApplicationContextInitializer<ConfigurableApplicationContext> {
 
+	private static final String GRPC_SERVER_STARTED_EVENT = "org.springframework.grpc.server.lifecycle.GrpcServerStartedEvent";
+
 	@Override
 	public void initialize(ConfigurableApplicationContext applicationContext) {
+		if (!ClassUtils.isPresent(GRPC_SERVER_STARTED_EVENT, applicationContext.getClassLoader())) {
+			return;
+		}
 		applicationContext.addApplicationListener(new Listener(applicationContext));
 	}
 

module/spring-boot-grpc-test/src/test/java/org/springframework/boot/grpc/test/autoconfigure/GrpcPortInfoApplicationContextInitializerTests.java

@@ -16,10 +16,13 @@
 
 package org.springframework.boot.grpc.test.autoconfigure;
 
+import java.io.IOException;
+
 import io.grpc.Server;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -43,6 +46,29 @@ class GrpcPortInfoApplicationContextInitializerTests {
 
 	private static final String PORT_PROPERTY = "local.grpc.server.port";
 
+	@Test
+	void whenGrpcServerStartedEventIsNotOnTheClasspathRegistersNoListener() throws IOException {
+		// gh-50825: the initializer is registered unconditionally via
+		// spring.factories, so with spring-grpc absent the listener's generic
+		// interface cannot be resolved and Spring throws TypeNotPresentException.
+		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+				FilteredClassLoader classLoader = new FilteredClassLoader(GrpcServerStartedEvent.class)) {
+			context.setClassLoader(classLoader);
+			int before = context.getApplicationListeners().size();
+			new GrpcPortInfoApplicationContextInitializer().initialize(context);
+			assertThat(context.getApplicationListeners()).hasSize(before);
+		}
+	}
+
+	@Test
+	void whenGrpcServerStartedEventIsOnTheClasspathRegistersListener() {
+		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext()) {
+			int before = context.getApplicationListeners().size();
+			new GrpcPortInfoApplicationContextInitializer().initialize(context);
+			assertThat(context.getApplicationListeners()).hasSize(before + 1);
+		}
+	}
+
 	@Test
 	void whenServerHasAddressInitializerSetsPortProperty() {
 		NettyGrpcServerFactory factory = mock();