OZG-4095 receive: Avoid exception on any null value

src/main/java/de/ozgcloud/nachrichten/postfach/osiv2/transfer/Osi2ResponseMapper.java

@@ -51,12 +51,11 @@ public interface Osi2ResponseMapper {
 
 	@Named("mapOffsetDateTimeToZoned")
 	default ZonedDateTime mapOffsetDateTimeToZoned(OffsetDateTime offsetDateTime) {
-		return offsetDateTime.toZonedDateTime();
+		return offsetDateTime == null ? null : offsetDateTime.toZonedDateTime();
 	}
 
 	@Named("mapMailBody")
 	default String mapMailBody(V1ReplyMessage message) {
-		// According to the API spec `body` is nullable
 		var body = mapNullToEmpty(message.getBody());
 		return Boolean.TRUE.equals(message.getIsHtml())
 				? Osi2HtmlDocument.renderToPlainText(body)
@@ -64,7 +63,9 @@ public interface Osi2ResponseMapper {
 	}
 
 	default PostfachAddress buildPostfachAddressByPostfachId(UUID messageBox) {
-		return PostfachAddress.builder()
+		return messageBox == null
+				? null
+				: PostfachAddress.builder()
 						.type(POSTFACH_ADDRESS_TYPE)
 						.version(POSTFACH_ADDRESS_VERSION)
 						.identifier(StringBasedIdentifier.builder()
@@ -76,7 +77,9 @@ public interface Osi2ResponseMapper {
 	}
 
 	default PostfachNachricht.ReplyOption mapReplyAction(V1ReplyBehavior replyOption) {
-		return switch (replyOption) {
+		return replyOption == null
+				? PostfachNachricht.ReplyOption.FORBIDDEN
+				: switch (replyOption) {
 					case REPLYFORBIDDEN -> PostfachNachricht.ReplyOption.FORBIDDEN;
 					case REPLYPOSSIBLE -> PostfachNachricht.ReplyOption.POSSIBLE;
 					case REPLYMANDATORY -> PostfachNachricht.ReplyOption.MANDATORY;

src/test/java/de/ozgcloud/nachrichten/postfach/osiv2/transfer/Osi2ResponseMapperTest.java

@@ -102,7 +102,8 @@ class Osi2ResponseMapperTest {
 			return Stream.of(
 					Arguments.of(V1ReplyBehavior.REPLYPOSSIBLE, PostfachNachricht.ReplyOption.POSSIBLE),
 					Arguments.of(V1ReplyBehavior.REPLYMANDATORY, PostfachNachricht.ReplyOption.MANDATORY),
-					Arguments.of(V1ReplyBehavior.REPLYFORBIDDEN, PostfachNachricht.ReplyOption.FORBIDDEN)
+					Arguments.of(V1ReplyBehavior.REPLYFORBIDDEN, PostfachNachricht.ReplyOption.FORBIDDEN),
+					Arguments.of(null, PostfachNachricht.ReplyOption.FORBIDDEN)
 			);
 		}
 
@@ -126,6 +127,25 @@ class Osi2ResponseMapperTest {
 			assertThat(result.getMessageId()).isEqualTo(MESSAGE_ID);
 		}
 
+		@DisplayName("should not fail if all fields are null")
+		@Test
+		void shouldNotFailIfAllFieldsAreNull() {
+			var nullMessage = new V1ReplyMessage();
+
+			assertThatCode(() -> mapper.toPostfachNachricht(nullMessage))
+					.doesNotThrowAnyException();
+		}
+
+		@DisplayName("should not fail if all fields are null and isHtml")
+		@Test
+		void shouldNotFailIfAllFieldsAreNullAndIsHtml() {
+			var nullMessage = new V1ReplyMessage()
+					.isHtml(true);
+
+			assertThatCode(() -> mapper.toPostfachNachricht(nullMessage))
+					.doesNotThrowAnyException();
+		}
+
 		private PostfachNachricht doMapping() {
 			return mapper.toPostfachNachricht(message);
 		}