diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index ffeeea1..9f4e048 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -31,10 +31,10 @@ jobs:
       - uses: actions/setup-java@v3
         with:
           distribution: temurin
-          java-version: 11
+          java-version: 17
           cache: maven
       - run: mvn -B -ntp dependency:go-offline
-      - run: mvn -B -ntp javadoc:javadoc-no-fork -Dmaven.javadoc.failOnWarnings=true -Ddoclint=all
+      - run: mvn -B -ntp javadoc:javadoc-no-fork -Ddoclint=all
 
   checkstyle:
     runs-on: ubuntu-latest
@@ -43,7 +43,7 @@ jobs:
       - uses: actions/setup-java@v3
         with:
           distribution: temurin
-          java-version: 11
+          java-version: 17
           cache: maven
       - run: mvn -B -ntp dependency:go-offline
       - run: mvn -B -ntp checkstyle:check
@@ -55,7 +55,7 @@ jobs:
       - uses: actions/setup-java@v3
         with:
           distribution: temurin
-          java-version: 11
+          java-version: 17
           cache: maven
           server-id: sonatype-nexus
           server-username: SERVER_USERNAME
diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 4f561a0..653e10d 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -18,7 +18,7 @@ jobs:
       - uses: actions/setup-java@v3
         with:
           distribution: temurin
-          java-version: 11
+          java-version: 17
           cache: maven
           server-id: sonatype-nexus
           server-username: SERVER_USERNAME
diff --git a/pom.xml b/pom.xml
index a279cf5..5e92f3d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -65,8 +65,8 @@
 
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
-		<maven.compiler.source>11</maven.compiler.source>
-		<maven.compiler.target>11</maven.compiler.target>
+		<maven.compiler.source>17</maven.compiler.source>
+		<maven.compiler.target>17</maven.compiler.target>
 		<maven.compiler.parameters>true</maven.compiler.parameters>
 		<maven.compiler.showDeprecation>true</maven.compiler.showDeprecation>
 		<maven.compiler.showWarnings>true</maven.compiler.showWarnings>
diff --git a/src/main/java/io/kokuwa/micronaut/logging/configurator/RootAutoSelectAppenderAction.java b/src/main/java/io/kokuwa/micronaut/logging/configurator/RootAutoSelectAppenderAction.java
index 1353690..74ce57f 100644
--- a/src/main/java/io/kokuwa/micronaut/logging/configurator/RootAutoSelectAppenderAction.java
+++ b/src/main/java/io/kokuwa/micronaut/logging/configurator/RootAutoSelectAppenderAction.java
@@ -70,21 +70,15 @@ public class RootAutoSelectAppenderAction extends Action {
 	private void setAppender(Logger rootLogger, String appenderName) {
 		addInfo("Use appender: " + appenderName);
 
-		Layout<ILoggingEvent> layout;
-		switch (appenderName) {
-			case APPENDER_JSON:
-				layout = json();
-				break;
-			case APPENDER_GCP:
-				layout = gcp();
-				break;
-			case APPENDER_CONSOLE:
-				layout = console();
-				break;
-			default:
+		Layout<ILoggingEvent> layout = switch (appenderName) {
+			case APPENDER_JSON -> json();
+			case APPENDER_GCP -> gcp();
+			case APPENDER_CONSOLE -> console();
+			default -> {
 				addError("Appender " + appenderName + " not found. Using console ...");
-				layout = console();
-		}
+				yield console();
+			}
+		};
 		layout.start();
 
 		var encoder = new LayoutWrappingEncoder<ILoggingEvent>();
diff --git a/src/main/java/io/kokuwa/micronaut/logging/http/mdc/HeaderMdcFilter.java b/src/main/java/io/kokuwa/micronaut/logging/http/mdc/HeaderMdcFilter.java
index a59b425..e9af261 100644
--- a/src/main/java/io/kokuwa/micronaut/logging/http/mdc/HeaderMdcFilter.java
+++ b/src/main/java/io/kokuwa/micronaut/logging/http/mdc/HeaderMdcFilter.java
@@ -40,7 +40,7 @@ public class HeaderMdcFilter extends AbstractMdcFilter {
 			@Value("${" + PREFIX + ".prefix}") Optional<String> prefix,
 			@Value("${" + PREFIX + ".order}") Optional<Integer> order) {
 		super(order.orElse(DEFAULT_ORDER), prefix.orElse(null));
-		this.headers = headers.stream().map(String::toLowerCase).collect(Collectors.toSet());
+		this.headers = headers.stream().map(String::toLowerCase).collect(Collectors.toUnmodifiableSet());
 		log.info("Configured with header names {}", headers);
 	}
 
@@ -48,9 +48,7 @@ public class HeaderMdcFilter extends AbstractMdcFilter {
 	public Publisher<MutableHttpResponse<?>> doFilter(HttpRequest<?> request, ServerFilterChain chain) {
 		var mdc = new HashMap<String, String>();
 		for (var header : headers) {
-			request.getHeaders()
-					.getFirst(header)
-					.ifPresent(value -> mdc.put(header, String.valueOf(value)));
+			request.getHeaders().getFirst(header).ifPresent(value -> mdc.put(header, String.valueOf(value)));
 		}
 		return doFilter(request, chain, mdc);
 	}