From a4475ef340a2dfa5aa123a86662f5d80ee36a7aa Mon Sep 17 00:00:00 2001
From: d044677 <j.denner@sap.com>
Date: Tue, 9 Jul 2024 08:10:39 +0200
Subject: [PATCH] AddHttpHeaderToLogContextFilter: Filter immediately for
 getField presence

* Previously the present of a field name was checked after fetchin the header value and then dropped.
  This can be done once and during initialization.
---
 .../filter/AddHttpHeadersToLogContextFilter.java    | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/cf-java-logging-support-servlet/src/main/java/com/sap/hcp/cf/logging/servlet/filter/AddHttpHeadersToLogContextFilter.java b/cf-java-logging-support-servlet/src/main/java/com/sap/hcp/cf/logging/servlet/filter/AddHttpHeadersToLogContextFilter.java
index 66c4f994..cbf4ccd6 100644
--- a/cf-java-logging-support-servlet/src/main/java/com/sap/hcp/cf/logging/servlet/filter/AddHttpHeadersToLogContextFilter.java
+++ b/cf-java-logging-support-servlet/src/main/java/com/sap/hcp/cf/logging/servlet/filter/AddHttpHeadersToLogContextFilter.java
@@ -6,7 +6,6 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
-import java.util.Objects;
 import java.util.stream.Stream;
 
 import javax.servlet.http.HttpServletRequest;
@@ -23,8 +22,8 @@
  */
 public class AddHttpHeadersToLogContextFilter extends AbstractLoggingFilter {
 
-    private List<HttpHeader> headers;
-    private List<String> fields;
+    private final List<HttpHeader> headers;
+    private final List<String> fields;
 
     /**
      * The default constructor uses {@link HttpHeaders#propagated()} to define
@@ -53,16 +52,16 @@ public AddHttpHeadersToLogContextFilter(HttpHeader... headers) {
      */
     public AddHttpHeadersToLogContextFilter(List<? extends HttpHeader> list, HttpHeader... custom) {
         Stream<HttpHeader> allHeaders = Stream.concat(list.stream(), Arrays.stream(custom));
-        this.headers = unmodifiableList(allHeaders.filter(HttpHeader::isPropagated).collect(toList()));
-        this.fields = unmodifiableList(headers.stream().map(HttpHeader::getField).filter(Objects::nonNull).collect(
-                                                                                                                   toList()));
+        this.headers = unmodifiableList(allHeaders
+                .filter(HttpHeader::isPropagated).filter(h -> h.getField() != null).collect(toList()));
+        this.fields = unmodifiableList(headers.stream().map(HttpHeader::getField).collect(toList()));
     }
 
     @Override
     protected void beforeFilter(HttpServletRequest request, HttpServletResponse response) {
         for (HttpHeader header: headers) {
             String headerValue = HttpHeaderUtilities.getHeaderValue(request, header);
-            if (header.getField() != null && headerValue != null) {
+            if (headerValue != null) {
                 LogContext.add(header.getField(), headerValue);
             }
         }