diff --git a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt
index b039795..e6da81e 100644
--- a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt
+++ b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/KorapXmlTool.kt
@@ -1648,7 +1648,7 @@
         } else {
             LOGGER.info("Processing zip files sequentially")
             Arrays.stream(zips).forEachOrdered { zipFilePath ->
-                processZipFileSequentially((zipFilePath ?: "").toString(), getFoundryFromZipFileNames(zips))
+                processZipFileSequentially(zipFilePath, getFoundryFromZipFileNames(zips))
             }
         }
 
@@ -3405,7 +3405,7 @@
             }
             
             if (outputFormat == OutputFormat.KRILL) {
-                processedTextsPerZip.getOrPut(zipPath.toString()) { mutableSetOf() }.add(docId)
+                processedTextsPerZip.getOrPut(zipPath) { mutableSetOf() }.add(docId)
             }
             
             val effectiveWaitForMorpho = if (fileName == "morpho.xml") true else waitForMorpho
@@ -4485,7 +4485,7 @@
                 XMLStreamConstants.END_ELEMENT -> {
                     if (reader.localName == "span") {
                         if (isSentence && currentFrom != null && currentTo != null) {
-                            list.add(Span(currentFrom!!, currentTo!!))
+                            list.add(Span(currentFrom, currentTo))
                         }
                         currentFrom = null
                         currentTo = null
@@ -4594,7 +4594,7 @@
                 line.isEmpty() -> {
                     // Sentence boundary: record the sentence span if available
                     if (sentenceStartOffset != null && sentenceEndOffset != null) {
-                        sentenceSpans.add(Span(sentenceStartOffset!!, sentenceEndOffset!!))
+                        sentenceSpans.add(Span(sentenceStartOffset, sentenceEndOffset))
                     }
                     sentenceStartOffset = null
                     sentenceEndOffset = null
@@ -4639,7 +4639,7 @@
 
         // If last sentence did not end with an empty line, capture it now
         if (sentenceStartOffset != null && sentenceEndOffset != null) {
-            sentenceSpans.add(Span(sentenceStartOffset!!, sentenceEndOffset!!))
+            sentenceSpans.add(Span(sentenceStartOffset, sentenceEndOffset))
         }
 
         if (morphoSpans.isEmpty()) {
@@ -4839,7 +4839,7 @@
 
         // Add final document
         if (currentTextId != null && currentFoundry != null && currentLines.isNotEmpty()) {
-            documents.add(ConlluDocument(currentTextId!!, currentFoundry!!, currentLines.toList()))
+            documents.add(ConlluDocument(currentTextId, currentFoundry, currentLines.toList()))
         }
 
         if (documents.isEmpty()) {
@@ -4899,7 +4899,7 @@
                         line.isEmpty() -> {
                             // Sentence boundary
                             if (sentenceStartOffset != null && sentenceEndOffset != null) {
-                                sentenceSpans.add(Span(sentenceStartOffset!!, sentenceEndOffset!!))
+                                sentenceSpans.add(Span(sentenceStartOffset, sentenceEndOffset))
                             }
                             sentenceStartOffset = null
                             sentenceEndOffset = null
@@ -4957,7 +4957,7 @@
 
                 // Capture final sentence if not ended with empty line
                 if (sentenceStartOffset != null && sentenceEndOffset != null) {
-                    sentenceSpans.add(Span(sentenceStartOffset!!, sentenceEndOffset!!))
+                    sentenceSpans.add(Span(sentenceStartOffset, sentenceEndOffset))
                 }
 
                 if (morphoSpans.isEmpty()) {
@@ -5449,7 +5449,7 @@
                 }
             }
             if (year != null && month != null && day != null) {
-                metadata["pubDate"] = "${year}-${month!!.padStart(2, '0')}-${day!!.padStart(2, '0')}"
+                metadata["pubDate"] = "${year}-${month.padStart(2, '0')}-${day.padStart(2, '0')}"
             }
 
             headerRoot.firstElement("ref") { it.getAttribute("type") == "page_url" }
@@ -5867,7 +5867,7 @@
                 is String -> currentValue.isBlank()
                 else -> false
             }
-            if (shouldInherit && value != null) {
+            if (shouldInherit) {
                 when (value) {
                     is String -> if (value.isNotBlank()) textData.headerMetadata[key] = value
                     is List<*> -> if (value.isNotEmpty()) textData.headerMetadata[key] = value
@@ -5884,7 +5884,7 @@
                 is String -> currentValue.isBlank()
                 else -> false
             }
-            if (shouldInherit && value != null) {
+            if (shouldInherit) {
                 when (value) {
                     is String -> if (value.isNotBlank()) textData.headerMetadata[key] = value
                     is List<*> -> if (value.isNotEmpty()) textData.headerMetadata[key] = value
diff --git a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/OpenNlpBridge.kt b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/OpenNlpBridge.kt
index ed435d1..3ade1c2 100644
--- a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/OpenNlpBridge.kt
+++ b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/OpenNlpBridge.kt
@@ -21,7 +21,7 @@
         synchronized(model) {
             if (POSmodel == null) {
                 logger.info("Initializing OpenNLP with model $model")
-                POSmodel = POSModel(File(model as String).inputStream())
+                POSmodel = POSModel(File(model).inputStream())
                 logger.info("Model $model loaded")
             }
         }
@@ -48,4 +48,4 @@
         }
     }
 
-}
\ No newline at end of file
+}
diff --git a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/formatters/KorapXmlFormatter.kt b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/formatters/KorapXmlFormatter.kt
index ec9a5aa..55c08b3 100644
--- a/app/src/main/kotlin/de/ids_mannheim/korapxmltools/formatters/KorapXmlFormatter.kt
+++ b/app/src/main/kotlin/de/ids_mannheim/korapxmltools/formatters/KorapXmlFormatter.kt
@@ -159,7 +159,7 @@
         val sortedKeys = context.morpho?.keys?.sortedBy { it.split("-")[0].toInt() }
 
         sortedKeys?.forEach { spanString ->
-            val mfs = context.morpho?.get(spanString)
+            val mfs = context.morpho[spanString]
             val offsets = spanString.split("-")
             if(offsets.size != 2) {
                 LOGGER.warning("Invalid span: $spanString in ${context.docId}")
diff --git a/app/src/test/kotlin/de/ids_mannheim/korapxmltools/ConlluConversionTest.kt b/app/src/test/kotlin/de/ids_mannheim/korapxmltools/ConlluConversionTest.kt
index fc6f806..7b9aa65 100644
--- a/app/src/test/kotlin/de/ids_mannheim/korapxmltools/ConlluConversionTest.kt
+++ b/app/src/test/kotlin/de/ids_mannheim/korapxmltools/ConlluConversionTest.kt
@@ -402,7 +402,7 @@
         val filenameLine = lines.find { it.startsWith("# filename = ") }
         assertNotNull(filenameLine, "Should have filename comment line")
         assertTrue(
-            filenameLine!!.contains("/spacy/morpho.xml"),
+            filenameLine.contains("/spacy/morpho.xml"),
             "Filename should point to spacy/morpho.xml, but was: $filenameLine"
         )
         assertFalse(
@@ -458,4 +458,4 @@
             outputDir.deleteRecursively()
         }
     }
-}
\ No newline at end of file
+}
diff --git a/app/src/test/kotlin/de/ids_mannheim/korapxmltools/SparseAnnotationExternalTest.kt b/app/src/test/kotlin/de/ids_mannheim/korapxmltools/SparseAnnotationExternalTest.kt
index f6fd655..e853ef2 100644
--- a/app/src/test/kotlin/de/ids_mannheim/korapxmltools/SparseAnnotationExternalTest.kt
+++ b/app/src/test/kotlin/de/ids_mannheim/korapxmltools/SparseAnnotationExternalTest.kt
@@ -10,13 +10,17 @@
 class SparseAnnotationExternalTest {
 
     private fun extractFileFromZip(zipFile: File, regex: Regex): String? {
-        val zip = org.apache.commons.compress.archivers.zip.ZipFile(zipFile)
-        val entry = zip.entries.asSequence().firstOrNull { regex.matches(it.name) }
-        return if (entry != null) {
-            zip.getInputStream(entry).bufferedReader().use { it.readText() }
-        } else {
-            null
-        }
+        return org.apache.commons.compress.archivers.zip.ZipFile.builder()
+            .setFile(zipFile)
+            .get()
+            .use { zip ->
+                val entry = zip.entries.asSequence().firstOrNull { regex.matches(it.name) }
+                if (entry != null) {
+                    zip.getInputStream(entry).bufferedReader().use { it.readText() }
+                } else {
+                    null
+                }
+            }
     }
 
     @Test
@@ -66,7 +70,7 @@
             // Verify that the annotation is on the correct span (32-34)
             // Note: Attribute order is not guaranteed, so check for attributes individually
             assertTrue(
-                morphoXml!!.contains("""from="32"""") && morphoXml.contains("""to="34""""),
+                morphoXml.contains("""from="32"""") && morphoXml.contains("""to="34""""),
                 "Annotation should be on span 32-34 (ID 7), but morpho.xml content was:\n$morphoXml"
             )
             
diff --git a/gradlew b/gradlew
index 1b6c787..f1c56bb 100755
--- a/gradlew
+++ b/gradlew
@@ -86,7 +86,7 @@
 APP_BASE_NAME=${0##*/}
 
 # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m" "-XX:+IgnoreUnrecognizedVMOptions" "--enable-native-access=ALL-UNNAMED"'
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
diff --git a/gradlew.bat b/gradlew.bat
index 107acd3..bb10664 100644
--- a/gradlew.bat
+++ b/gradlew.bat
@@ -33,7 +33,7 @@
 for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
 
 @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m" "-XX:+IgnoreUnrecognizedVMOptions" "--enable-native-access=ALL-UNNAMED"
 
 @rem Find java.exe
 if defined JAVA_HOME goto findJavaFromJavaHome