diff --git a/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/VTypeRef.java b/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/VTypeRef.java
index 19198922b084d1bd77a205fdd4fbe71afd70f9bd..9852ee9401385fc74ee9dafb1773c9322128e45b 100644
--- a/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/VTypeRef.java
+++ b/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/VTypeRef.java
@@ -9,7 +9,6 @@ import de.unikoblenz.fgbks.base.utils.boundary.impl.InvalidBoundary;
 import de.unikoblenz.fgbks.base.utils.boundary.impl.LongBoundary;
 import de.unikoblenz.fgbks.base.utils.boundary.impl.StringBoundary;
 import java.time.LocalDateTime;
-import java.util.Optional;
 import org.camunda.bpm.model.dmn.instance.TypeRef;
 
 /**
@@ -103,11 +102,11 @@ public enum VTypeRef {
    * @param text the String to parse the new {@link Boundary}
    * @return a Optional of a new {@link Boundary}
    */
-  public Optional<Boundary> getBoundaryFromText(String text) {
+  public Boundary getBoundaryFromText(String text) {
     try {
-      return Optional.of(boundaryClass.getDeclaredConstructor(String.class).newInstance(text));
+      return boundaryClass.getDeclaredConstructor(String.class).newInstance(text);
     } catch (Exception ignored) {
-      return Optional.of(InvalidBoundary.getInstance());
+      return InvalidBoundary.getInstance();
     }
   }
 
diff --git a/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/impl/VDmnInputValueImpl.java b/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/impl/VDmnInputValueImpl.java
index 30130748fa81435b00f2637935604ec71192b855..9308d56d499df5d1b3b4da8df23656d73b0c5f94 100644
--- a/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/impl/VDmnInputValueImpl.java
+++ b/dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/domain/vdmn/impl/VDmnInputValueImpl.java
@@ -73,7 +73,7 @@ public class VDmnInputValueImpl extends VDmnValueImpl implements VDmnInputValue
       // create boundary, if not created before
       if (value.boundary == null) {
         value.boundary =
-            value.dmnColumn.getTypeRef().getBoundaryFromText(value.getText()).orElse(null);
+            value.dmnColumn.getTypeRef().getBoundaryFromText(value.getText());
       }
       return super.build();
     }
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractCheckerTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractCheckerTest.java
index 8e5b5ddb789435f7af60d93ce7e7c619e3592c55..b8c9aa9ca424d6d745f7f029c20380d5f0c686ba 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractCheckerTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractCheckerTest.java
@@ -25,7 +25,7 @@ public abstract class AbstractCheckerTest {
   }
 
   private void doCheck(VTypeRef type, String b1, String b2, boolean expected) {
-    doCheck(type.getBoundaryFromText(b1).get(), type.getBoundaryFromText(b2).get(), expected);
+    doCheck(type.getBoundaryFromText(b1), type.getBoundaryFromText(b2), expected);
   }
 
   private void doCheck(Boundary b1, Boundary b2, boolean expected) {
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractStringCheckerTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractStringCheckerTest.java
index 18cd2b2afc2a1dd630f0b491059f14cb28c71e41..eeb8395e25895f45134767beb99e8493c640b75b 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractStringCheckerTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/AbstractStringCheckerTest.java
@@ -19,7 +19,7 @@ public abstract class AbstractStringCheckerTest {
   }
 
   private void doCheck(VTypeRef type, String b1, String b2, boolean expected) {
-    doCheck(type.getBoundaryFromText(b1).get(), type.getBoundaryFromText(b2).get(), expected);
+    doCheck(type.getBoundaryFromText(b1), type.getBoundaryFromText(b2), expected);
   }
 
   private void doCheck(Boundary b1, Boundary b2, boolean expected) {
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringInContactTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringInContactTest.java
index 0e4bddcd2cc067c1fcfdfa4a500bf6bbcf9153c8..60f818224cd03563d8d8d4aae1b21a5dc7f002e6 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringInContactTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringInContactTest.java
@@ -15,7 +15,7 @@ class CheckStringInContactTest extends AbstractStringCheckerTest {
     doStringCheck("\"a\"", "not(\"b\")", true);
     doStringCheck("\"a\"", "\"a\",\"b\"", true);
     doStringCheck("\"a\"", "\"c\",\"b\"", false);
-    doStringCheck("\"a\"", "not(\"a\",\"b\")", true);
+    doStringCheck("\"a\"", "not(\"a\",\"b\")", false);
     doStringCheck("\"a\"", "not(\"c\",\"b\")", true);
     doStringCheck("", "not(\"c\",\"b\")", true);
     doStringCheck("", "\"c\",\"b\"", true);
diff --git a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringNotInContactTest.java b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringNotInContactTest.java
index 6d4e0e3c7270a635f4933ec39600f992fbc7f755..07f94e5a9375ed55edfc9aa28c832ae78c9a6517 100644
--- a/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringNotInContactTest.java
+++ b/dmnverifierapi/src/test/java/de/unikoblenz/fgbks/base/utils/boundary/checker/CheckStringNotInContactTest.java
@@ -15,7 +15,7 @@ class CheckStringNotInContactTest extends AbstractStringCheckerTest {
     doStringCheck("\"a\"", "not(\"b\")", false);
     doStringCheck("\"a\"", "\"a\",\"b\"", false);
     doStringCheck("\"a\"", "\"c\",\"b\"", true);
-    doStringCheck("\"a\"", "not(\"a\",\"b\")", false);
+    doStringCheck("\"a\"", "not(\"a\",\"b\")", true);
     doStringCheck("\"a\"", "not(\"c\",\"b\")", false);
   }