fix a NullPointerException.

gh-16044

Author: nosan

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/web/trace/reactive/ServerWebExchangeTraceableRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -16,10 +16,13 @@
 
 package org.springframework.boot.actuate.web.trace.reactive;
 
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
 import java.net.URI;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 import org.springframework.boot.actuate.trace.http.TraceableRequest;
 import org.springframework.http.server.reactive.ServerHttpRequest;
@@ -45,8 +48,9 @@ class ServerWebExchangeTraceableRequest implements TraceableRequest {
 		this.method = request.getMethodValue();
 		this.headers = request.getHeaders();
 		this.uri = request.getURI();
-		this.remoteAddress = (request.getRemoteAddress() != null)
-				? request.getRemoteAddress().getAddress().toString() : null;
+		this.remoteAddress = Optional.ofNullable(request.getRemoteAddress())
+				.map(InetSocketAddress::getAddress).map(InetAddress::toString)
+				.orElse(null);
 	}
 
 	@Override