Discard blank keys in PropertiesUtil

Author: vy

log4j-api/src/main/java/org/apache/logging/log4j/util/PropertiesUtil.java

@@ -536,7 +536,7 @@ private synchronized void reload() {
             final Set<String> keys = new HashSet<>();
             sources.stream().map(PropertySource::getPropertyNames).forEach(keys::addAll);
             // 2. Fills the property caches. Sources with higher priority values don't override the previous ones.
-            keys.stream().filter(Objects::nonNull).forEach(key -> {
+            keys.stream().filter(Strings::isNotBlank).forEach(key -> {
                 final List<CharSequence> tokens = PropertySource.Util.tokenize(key);
                 final boolean hasTokens = !tokens.isEmpty();
                 sources.forEach(source -> {

src/changelog/.2.x.x/2414_fix_blank_keys_in_PropertiesUtil.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="https://logging.apache.org/xml/ns"
+       xsi:schemaLocation="https://logging.apache.org/xml/ns https://logging.apache.org/xml/ns/log4j-changelog-0.xsd"
+       type="fixed">
+  <issue id="2414" link="https://github.com/apache/logging-log4j2/issues/2414"/>
+  <description format="asciidoc">Discard blank keys in `PropertiesUtil`</description>
+</entry>