Fix potential NPE in GraylogExtendedLogFormatProperties

Signed-off-by: Dmytro Nosan <dimanosan@gmail.com>

See gh-43863

Author: nosan

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/structured/GraylogExtendedLogFormatProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -34,6 +34,11 @@ public record GraylogExtendedLogFormatProperties(String host, Service service) {
 
 	static final GraylogExtendedLogFormatProperties NONE = new GraylogExtendedLogFormatProperties(null, Service.NONE);
 
+	public GraylogExtendedLogFormatProperties(String host, Service service) {
+		this.host = host;
+		this.service = (service != null) ? service : Service.NONE;
+	}
+
 	GraylogExtendedLogFormatProperties withDefaults(Environment environment) {
 		String name = withFallbackProperty(environment, this.host, "spring.application.name");
 		Service service = this.service.withDefaults(environment);

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/structured/GraylogExtendedLogFormatPropertiesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -41,6 +41,23 @@ void getBindsFromEnvironment() {
 		assertThat(properties).isEqualTo(new GraylogExtendedLogFormatProperties("spring", new Service("1.2.3")));
 	}
 
+	@Test
+	void getBindsFromEnvironmentWhenHostIsPresentAndServiceIsMissing() {
+		MockEnvironment environment = new MockEnvironment();
+		environment.setProperty("logging.structured.gelf.host", "spring");
+		GraylogExtendedLogFormatProperties properties = GraylogExtendedLogFormatProperties.get(environment);
+		assertThat(properties).isEqualTo(new GraylogExtendedLogFormatProperties("spring", Service.NONE));
+	}
+
+	@Test
+	void getBindsFromEnvironmentWhenHostIsPresentAndServiceIsMissingUsesApplicationVersion() {
+		MockEnvironment environment = new MockEnvironment();
+		environment.setProperty("logging.structured.gelf.host", "spring");
+		environment.setProperty("spring.application.version", "1.2.3");
+		GraylogExtendedLogFormatProperties properties = GraylogExtendedLogFormatProperties.get(environment);
+		assertThat(properties).isEqualTo(new GraylogExtendedLogFormatProperties("spring", new Service("1.2.3")));
+	}
+
 	@Test
 	void getWhenNoServiceNameUsesApplicationName() {
 		MockEnvironment environment = new MockEnvironment();