diff --git a/layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/utils/MarkedContentUtils.java b/layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/utils/MarkedContentUtils.java
index af4676f..799ac99 100644
--- a/layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/utils/MarkedContentUtils.java
+++ b/layoutparser-service/layoutparser-service-processor/src/main/java/com/knecon/fforesight/service/layoutparser/processor/utils/MarkedContentUtils.java
@@ -9,6 +9,7 @@ import org.apache.pdfbox.text.TextPosition;
 
 import java.awt.geom.Rectangle2D;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -22,7 +23,7 @@ public class MarkedContentUtils {
     public List<Rectangle2D> getMarkedContentBboxPerLine(List<PDMarkedContent> markedContents, String subtype) {
 
         if (markedContents == null) {
-            return null;
+            return Collections.emptyList();
         }
 
         var markedContentByYPosition = markedContents.stream()
@@ -37,7 +38,7 @@ public class MarkedContentUtils {
                 .collect(Collectors.groupingBy(TextPosition::getY));
 
         if (markedContentByYPosition.isEmpty()) {
-            return null;
+            return Collections.emptyList();
         }
 
         return markedContentByYPosition.values().stream()
diff --git a/layoutparser-service/layoutparser-service-server/src/test/java/com/knecon/fforesight/service/layoutparser/server/graph/ExtractMarkedContentTest.java b/layoutparser-service/layoutparser-service-server/src/test/java/com/knecon/fforesight/service/layoutparser/server/graph/ExtractMarkedContentTest.java
index a811fe7..176ed49 100644
--- a/layoutparser-service/layoutparser-service-server/src/test/java/com/knecon/fforesight/service/layoutparser/server/graph/ExtractMarkedContentTest.java
+++ b/layoutparser-service/layoutparser-service-server/src/test/java/com/knecon/fforesight/service/layoutparser/server/graph/ExtractMarkedContentTest.java
@@ -53,7 +53,9 @@ public class ExtractMarkedContentTest {
     @SneakyThrows
     public void testExtractTestWPhromma() throws IOException {
         System.out.printf("\n\n===\n%s\n===\n", "testWPhromma.pdf");
-            PDDocument document = Loader.loadPDF(new ClassPathResource("files/bdr/Drucksache_19_9865.pdf").getFile());
+        PDDocument document = null;
+        try {
+            document = Loader.loadPDF(new ClassPathResource("files/bdr/Drucksache_19_9865.pdf").getFile());
 
             Map<PDPage, Map<Integer, PDMarkedContent>> markedContents = new HashMap<>();
 
@@ -70,6 +72,10 @@ public class ExtractMarkedContentTest {
 
             PDStructureNode root = document.getDocumentCatalog().getStructureTreeRoot();
             showStructure(root, markedContents);
+        } finally {
+            if (null != document )
+                document.close();
+        }
     }
 
     /**
@@ -87,7 +93,10 @@ public class ExtractMarkedContentTest {
     @Test
     public void testExtractResMultipage() throws IOException {
         System.out.printf("\n\n===\n%s\n===\n", "res_multipage.pdf");
-            PDDocument document = Loader.loadPDF(new ClassPathResource("files/bdr/Drucksache_19_9865.pdf").getFile());
+
+        PDDocument document = null;
+        try {
+            document = Loader.loadPDF(new ClassPathResource("files/bdr/Drucksache_19_9865.pdf").getFile());
 
             Map<PDPage, Map<Integer, PDMarkedContent>> markedContents = new HashMap<>();
 
@@ -104,6 +113,10 @@ public class ExtractMarkedContentTest {
 
             PDStructureNode root = document.getDocumentCatalog().getStructureTreeRoot();
             showStructure(root, markedContents);
+        } finally {
+            if (document != null)
+                document.close();
+        }
     }
 
     /**
@@ -121,7 +134,9 @@ public class ExtractMarkedContentTest {
     @Test
     public void testExtractDailyReport() throws IOException {
         System.out.printf("\n\n===\n%s\n===\n", "Daily Report.pdf");
-            PDDocument document = Loader.loadPDF(new ClassPathResource("files/bdr/Drucksache_19_9865.pdf").getFile());
+        PDDocument document = null;
+        try {
+            document = Loader.loadPDF(new ClassPathResource("files/bdr/Drucksache_19_9865.pdf").getFile());
 
             Map<PDPage, Map<Integer, PDMarkedContent>> markedContents = new HashMap<>();
 
@@ -138,7 +153,11 @@ public class ExtractMarkedContentTest {
 
             PDStructureNode root = document.getDocumentCatalog().getStructureTreeRoot();
             showStructure(root, markedContents);
+        } finally {
+            if (null != document)
+                document.close();
         }
+    }
 
     /**
      * @see #testExtractTestWPhromma()