Polish Log4j2 changes

See gh-32742

spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/logging.adoc

@@ -487,7 +487,7 @@ NOTE: Because the standard `log4j2.xml` configuration file is loaded too early,
 You need to either use `log4j2-spring.xml` or define a configprop:logging.config[] property.
 
 NOTE: The extensions supersede the https://logging.apache.org/log4j/2.x/log4j-spring-boot/index.html[Spring Boot support] provided by Log4J.
-You should make sure not include the `org.apache.logging.log4j:log4j-spring-boot` module in your build.
+You should make sure not to include the `org.apache.logging.log4j:log4j-spring-boot` module in your build.
 
 
 
@@ -536,12 +536,12 @@ NOTE: The lookup key should be specified in kebab case (such as `my.property-nam
 
 
 
-[[features.logging.log4j2-extensions.environment-peroperty-source]]
+[[features.logging.log4j2-extensions.environment-property-source]]
 ==== Log4j2 System Properties
-Log4j2 supports a number of https://logging.apache.org/log4j/2.x/manual/configuration.html#SystemProperties[System Properties] that can be used configure various items.
+Log4j2 supports a number of https://logging.apache.org/log4j/2.x/manual/configuration.html#SystemProperties[System Properties] that can be used to configure various items.
 For example, the `log4j2.skipJansi` system property can be used to configure if the `ConsoleAppender` will try to use a https://github.com/fusesource/jansi[Jansi] output stream on Windows.
 
-All system properties that are loaded after the Log4J initialization can be obtained from the Spring `Environment`.
+All system properties that are loaded after the Log4j2 initialization can be obtained from the Spring `Environment`.
 For example, you could add `log4j2.skipJansi=false` to your `application.properties` file to have the `ConsoleAppender` use a Jansi on Windows.
 
 NOTE: The Spring `Environment` is only considered when system properties and OS environment variables do not contain the value being loaded.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/SpringEnvironmentLookup.java

@@ -44,7 +44,7 @@ class SpringEnvironmentLookup implements LoggerContextAware, StrLookup {
 	@Override
 	public String lookup(String key) {
 		Assert.state(this.environment != null, "Unable to obtain Spring Environment from LoggerContext");
-		return (this.environment != null) ? this.environment.getProperty(key) : null;
+		return this.environment.getProperty(key);
 	}
 
 	@Override

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/SpringProfileArbiter.java

@@ -64,7 +64,7 @@ final class SpringProfileArbiter implements Arbiter {
 	/**
 	 * Standard Builder to create the Arbiter.
 	 */
-	public static final class Builder implements org.apache.logging.log4j.core.util.Builder<SpringProfileArbiter> {
+	static final class Builder implements org.apache.logging.log4j.core.util.Builder<SpringProfileArbiter> {
 
 		private static final Logger statusLogger = StatusLogger.getLogger();
 
@@ -86,7 +86,7 @@ final class SpringProfileArbiter implements Arbiter {
 		 * @return this
 		 * @see Profiles#of(String...)
 		 */
-		public Builder setName(String name) {
+		Builder setName(String name) {
 			this.name = name;
 			return this;
 		}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4J2LoggingSystemTests.java

@@ -463,11 +463,10 @@ class Log4J2LoggingSystemTests extends AbstractLoggingSystemTests {
 
 	@Test
 	void initializeAddsSpringEnvironmentPropertySource() {
-		PropertiesUtil properties = PropertiesUtil.getProperties();
 		this.environment.setProperty("spring", "boot");
 		this.loggingSystem.beforeInitialize();
 		this.loggingSystem.initialize(this.initializationContext, null, null);
-		properties = PropertiesUtil.getProperties();
+		PropertiesUtil properties = PropertiesUtil.getProperties();
 		assertThat(properties.getStringProperty("spring")).isEqualTo("boot");
 	}
 

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/SpringEnvironmentLookupTests.java

@@ -68,7 +68,7 @@ class SpringEnvironmentLookupTests {
 	void lookupWhenNoSpringEnvironmentThrowsException() {
 		this.loggerContext.removeObject(Log4J2LoggingSystem.ENVIRONMENT_KEY);
 		Interpolator lookup = createLookup(this.loggerContext);
-		assertThatIllegalStateException().isThrownBy(() -> assertThat(lookup.lookup("spring:test")).isEqualTo("test"))
+		assertThatIllegalStateException().isThrownBy(() -> lookup.lookup("spring:test"))
 				.withMessage("Unable to obtain Spring Environment from LoggerContext");
 	}
 

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/SpringProfileArbiterTests.java

@@ -154,9 +154,7 @@ class SpringProfileArbiterTests {
 
 	private String getPackageResource(String fileName) {
 		String path = ClassUtils.getPackageName(getClass());
-		path = path.replace('.', '/');
-		path = path + "/" + fileName;
-		return "src/test/resources/" + path;
+		return "src/test/resources/" + path.replace('.', '/') + "/" + fileName;
 	}
 
 }

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/TestLog4J2LoggingSystem.java

@@ -25,7 +25,7 @@ import org.apache.logging.log4j.core.config.Configuration;
 
 class TestLog4J2LoggingSystem extends Log4J2LoggingSystem {
 
-	private List<String> availableClasses = new ArrayList<>();
+	private final List<String> availableClasses = new ArrayList<>();
 
 	TestLog4J2LoggingSystem() {
 		super(TestLog4J2LoggingSystem.class.getClassLoader());