Only set default configuration name if none has been previously set (#3454)

`AbstractConfiguration#setToDefault()` - only sets default configuration name if none has been previously set,

- added test for this change
- added changelog entry

Author: JWT007

log4j-core-test/src/test/java/org/apache/logging/log4j/core/config/Configurator1Test.java

@@ -332,7 +332,7 @@ void testNoLoggers() {
         LogManager.getLogger("org.apache.test.TestConfigurator");
         final Configuration config = ctx.getConfiguration();
         assertNotNull(config, "No configuration");
-        final String name = DefaultConfiguration.DEFAULT_NAME + "@" + Integer.toHexString(config.hashCode());
+        final String name = "Configurator1Test.testNoLoggers";
         assertEquals(name, config.getName(), "Unexpected Configuration.");
     }
 

log4j-core-test/src/test/java/org/apache/logging/log4j/core/config/Log4j_3431_Test.java

@@ -0,0 +1,89 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you 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
+ *
+ *      http://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.
+ */
+package org.apache.logging.log4j.core.config;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.builder.api.ConfigurationBuilderFactory;
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests the change for Log4j issue #3431.
+ * <p>
+ *   The configuration name should not be set to a default if a name already exists.
+ * </p>
+ *
+ * @see <a href="https://github.com/apache/logging-log4j2/issues/3431"/>
+ */
+@SuppressWarnings("NewClassNamingConvention")
+class Log4j_3431_Test {
+
+    /**
+     * Tests that the name of a configurations with no defined loggers is <strong>not</strong> reset when
+     * the configuration is started.
+     */
+    @Test
+    void testConfigurationDefaults_WithName() {
+
+        try (final LoggerContext ctx = new LoggerContext("Log4j_3431_Test")) {
+
+            final String name = "Log4j_3431_Configuration";
+
+            Configuration config = ConfigurationBuilderFactory.newConfigurationBuilder()
+                    .setConfigurationName(name)
+                    .setConfigurationSource(ConfigurationSource.NULL_SOURCE)
+                    .build(false);
+
+            // a configuration with no defined loggers should trigger AbstractConfiguration 'setToDefault()'
+            //   from 'doConfigure()'
+
+            ctx.start(config);
+
+            assertEquals(name, config.getName(), "The name of the configuration should be '" + name + "'");
+        }
+    }
+
+    /**
+     * Tests that the name of a configurations with no defined loggers is set to a default when
+     * the configuration is started.
+     */
+    @Test
+    void testConfigurationDefaults_WithNoName() {
+
+        try (final LoggerContext ctx = new LoggerContext("Log4j_3431_Test")) {
+
+            final String name = "Log4j_3431_Configuration";
+
+            Configuration config = ConfigurationBuilderFactory.newConfigurationBuilder()
+                    .setConfigurationSource(ConfigurationSource.NULL_SOURCE)
+                    .build(false);
+
+            // a configuration with no defined loggers should trigger AbstractConfiguration 'setToDefault()'
+            //   from 'doConfigure()'
+
+            ctx.start(config);
+
+            final String expectedPrefix = DefaultConfiguration.DEFAULT_NAME + "@";
+            Assertions.assertThatCharSequence(config.getName())
+                    .withFailMessage("The name of the configuration should start with '" + expectedPrefix + "'.")
+                    .isNotBlank()
+                    .startsWith(expectedPrefix);
+        }
+    }
+}

log4j-core-test/src/test/resources/bad/log4j-loggers.xml

@@ -15,7 +15,7 @@
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
   -->
-<Configuration status="OFF" name="XMLConfigTest">
+<Configuration status="OFF" name="Configurator1Test.testNoLoggers">
   <Properties>
     <Property name="filename">target/test.log</Property>
   </Properties>

log4j-core/src/main/java/org/apache/logging/log4j/core/config/AbstractConfiguration.java

@@ -78,6 +78,7 @@
 import org.apache.logging.log4j.status.StatusLogger;
 import org.apache.logging.log4j.util.LoaderUtil;
 import org.apache.logging.log4j.util.PropertiesUtil;
+import org.apache.logging.log4j.util.Strings;
 
 /**
  * The base Configuration. Many configuration implementations will extend this class.
@@ -774,8 +775,11 @@ public static Level getDefaultLevel() {
     }
 
     protected void setToDefault() {
-        // LOG4J2-1176 facilitate memory leak investigation
-        setName(DefaultConfiguration.DEFAULT_NAME + "@" + Integer.toHexString(hashCode()));
+        // LOG4J2-3431 don't set a default name if one has already been set
+        if (Strings.isBlank(getName())) {
+            // LOG4J2-1176 facilitate memory leak investigation
+            setName(DefaultConfiguration.DEFAULT_NAME + "@" + Integer.toHexString(hashCode()));
+        }
         final Appender appender = ConsoleAppender.createDefaultAppenderForLayout(DefaultLayout.INSTANCE);
         appender.start();
         addAppender(appender);

src/changelog/.2.x.x/3431_default_config_name.xml

@@ -0,0 +1,10 @@
+<?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="changed">
+  <issue id="3431" link="https://github.com/apache/logging-log4j2/issues/3431"/>
+  <description format="asciidoc">
+    Don't overwrite configured configuration name if the configuration has no loggers / no root logger.
+  </description>
+</entry>