diff --git a/src/main/java/de/ozgcloud/xta/test/app/config/XTAServer.java b/src/main/java/de/ozgcloud/xta/test/app/config/XTAServer.java
index be7b9731318139ff1f98f4bb007b0bcb201d3c0c..f5fd91b9978836dc5d771de05e2941b235a17cba 100644
--- a/src/main/java/de/ozgcloud/xta/test/app/config/XTAServer.java
+++ b/src/main/java/de/ozgcloud/xta/test/app/config/XTAServer.java
@@ -5,21 +5,21 @@ import jakarta.xml.ws.soap.SOAPBinding;
 
 import org.apache.cxf.bus.spring.SpringBus;
 import org.apache.cxf.jaxws.EndpointImpl;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
 import genv3.de.xoev.transport.xta.x211.ManagementPortType;
 import genv3.de.xoev.transport.xta.x211.MsgBoxPortType;
 import genv3.de.xoev.transport.xta.x211.SendPortType;
+import lombok.RequiredArgsConstructor;
 import lombok.extern.log4j.Log4j2;
 
 @Configuration
 @Log4j2
+@RequiredArgsConstructor
 public class XTAServer {
 
-	@Autowired
-	private SpringBus bus;
+	private final SpringBus bus;
 
 	@Bean
 	Endpoint managementEndpoint(final ManagementPortType managementPortType) {
diff --git a/src/main/java/de/ozgcloud/xta/test/app/model/XtaFile.java b/src/main/java/de/ozgcloud/xta/test/app/model/XtaFile.java
index 1a824a7cdd277b6b61ffee04a07ed3159dd45b9c..0a8319c41688eb9133a12e4b7f905f4c02cdbc62 100644
--- a/src/main/java/de/ozgcloud/xta/test/app/model/XtaFile.java
+++ b/src/main/java/de/ozgcloud/xta/test/app/model/XtaFile.java
@@ -19,6 +19,6 @@ public record XtaFile(
 		@NotBlank String name,
 		@Nullable String id,
 		@Nullable String language,
-		@NotNull @PositiveOrZero BigInteger size
+		@PositiveOrZero BigInteger size
 ) {
 }
diff --git a/src/main/java/de/ozgcloud/xta/test/app/model/XtaLookupServiceRequest.java b/src/main/java/de/ozgcloud/xta/test/app/model/XtaLookupServiceRequest.java
index 3ed26844a4771f2a760458fe864c840c5889f904..02572b41827dd6527093b94a5accba193c66a0cc 100644
--- a/src/main/java/de/ozgcloud/xta/test/app/model/XtaLookupServiceRequest.java
+++ b/src/main/java/de/ozgcloud/xta/test/app/model/XtaLookupServiceRequest.java
@@ -1,14 +1,13 @@
 package de.ozgcloud.xta.test.app.model;
 
 import jakarta.validation.constraints.NotBlank;
-import jakarta.validation.constraints.NotNull;
 
 import lombok.Builder;
 
 @Builder
 public record XtaLookupServiceRequest(
-		@NotNull @NotBlank String service,
-		@NotNull @NotBlank String readerIdentifierValue,
-		@NotNull @NotBlank String authorIdentifierValue
+		@NotBlank String service,
+		@NotBlank String readerIdentifierValue,
+		@NotBlank String authorIdentifierValue
 ) {
 }
diff --git a/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaData.java b/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaData.java
index 167a64d0be7ef786c7c5833a460b7898e8c1a96c..458ee204f855a675ccd767a58960d643fea7286a 100644
--- a/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaData.java
+++ b/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaData.java
@@ -15,8 +15,8 @@ import lombok.Builder;
 
 @Builder(toBuilder = true)
 public record XtaMessageMetaData(
-		@NotNull @NotBlank String service,
-		@NotNull @NotBlank String businessScenarioCode,
+		@NotBlank String service,
+		@NotBlank String businessScenarioCode,
 		@Nullable String businessScenarioName,
 		@Nullable String businessScenarioListUri,
 		@Nullable String businessScenarioListVersionId,
@@ -25,6 +25,6 @@ public record XtaMessageMetaData(
 		@ValidXtaId(namespace = MESSAGE_ID_NAMESPACE) String messageId,
 		@NotNull @Valid XtaIdentifier authorIdentifier,
 		@NotNull @Valid XtaIdentifier readerIdentifier,
-		@NotNull @PositiveOrZero BigInteger messageSize
+		@PositiveOrZero BigInteger messageSize
 ) {
 }
diff --git a/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListing.java b/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListing.java
index 72f1977c4b282334d6acccef5a0230b29997f381..d4c37bbd5e02657821b9db740f695051368c4156 100644
--- a/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListing.java
+++ b/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListing.java
@@ -4,7 +4,6 @@ import java.math.BigInteger;
 import java.util.List;
 
 import jakarta.validation.Valid;
-import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.PositiveOrZero;
 
@@ -12,7 +11,7 @@ import lombok.Builder;
 
 @Builder
 public record XtaMessageMetaDataListing(
-		@NotNull @PositiveOrZero BigInteger pendingMessageCount,
-		@NotNull @Valid List<XtaMessageMetaData> messages
+		@PositiveOrZero BigInteger pendingMessageCount,
+		@NotNull List<@Valid XtaMessageMetaData> messages
 ) {
 }
diff --git a/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListingRequest.java b/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListingRequest.java
index a5c011121b4f57e5f67168bbb8f63c229ed6413c..279014fb4fe85325d03b34115d211f87eebadc8a 100644
--- a/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListingRequest.java
+++ b/src/main/java/de/ozgcloud/xta/test/app/model/XtaMessageMetaDataListingRequest.java
@@ -1,14 +1,13 @@
 package de.ozgcloud.xta.test.app.model;
 
 import jakarta.validation.constraints.NotBlank;
-import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Positive;
 
 import lombok.Builder;
 
 @Builder
 public record XtaMessageMetaDataListingRequest(
-		@NotNull @NotBlank String clientIdentifierValue,
-		@NotNull @Positive int maxListItems
+		@NotBlank String clientIdentifierValue,
+		@Positive int maxListItems
 ) {
 }
diff --git a/src/test/java/de/ozgcloud/xta/test/app/validation/RequestValidatorTest.java b/src/test/java/de/ozgcloud/xta/test/app/validation/RequestValidatorTest.java
index cb46fc56d20adac55b181fcc3998b489ae2900a7..23e1264662d7708b41a6581aadbc66eae21c45e8 100644
--- a/src/test/java/de/ozgcloud/xta/test/app/validation/RequestValidatorTest.java
+++ b/src/test/java/de/ozgcloud/xta/test/app/validation/RequestValidatorTest.java
@@ -72,6 +72,16 @@ class RequestValidatorTest {
 
 				assertThatThrownBy(() -> validator.validate(request)).isEqualTo(exception);
 			}
+
+			@DisplayName("should throw if clientIdentifierValue is null")
+			@Test
+			void shouldThrowIfClientIdentifierValueIsNull() {
+				var request = XtaGetMessageRequestTestFactory.createBuilder()
+						.clientIdentifierValue(null)
+						.build();
+
+				assertThatThrownBy(() -> validator.validate(request)).isEqualTo(exception);
+			}
 		}
 
 	}