Add nullability annotations to smoke-test/spring-boot-smoke-test-structured-logging-log4j2

See gh-46587

Author: mhalbritter

smoke-test/spring-boot-smoke-test-structured-logging-log4j2/src/main/java/smoketest/structuredlogging/log4j2/CustomStructuredLogFormatter.java

@@ -18,13 +18,14 @@
 
 import org.apache.logging.log4j.core.LogEvent;
 import org.apache.logging.log4j.core.impl.ThrowableProxy;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.logging.structured.StructuredLogFormatter;
 import org.springframework.core.env.Environment;
 
 public class CustomStructuredLogFormatter implements StructuredLogFormatter<LogEvent> {
 
-	private final Long pid;
+	private final @Nullable Long pid;
 
 	public CustomStructuredLogFormatter(Environment environment) {
 		this.pid = environment.getProperty("spring.application.pid", Long.class);

smoke-test/spring-boot-smoke-test-structured-logging-log4j2/src/main/java/smoketest/structuredlogging/log4j2/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@NullMarked
+package smoketest.structuredlogging.log4j2;
+
+import org.jspecify.annotations.NullMarked;