diff --git a/pom.xml b/pom.xml
index 6df5f46..eb35304 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1,11 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>4.0.2</version>
+        <version>4.0.4</version>
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
 
@@ -16,8 +17,8 @@
 
     <properties>
         <java.version>25</java.version>
-        <errorprone.version>2.46.0</errorprone.version>
-        <nullaway.version>0.12.15</nullaway.version>
+        <errorprone.version>2.48.0</errorprone.version>
+        <nullaway.version>0.13.1</nullaway.version>
     </properties>
 
     <dependencyManagement>
@@ -25,12 +26,12 @@
             <dependency>
                 <groupId>it.aboutbits</groupId>
                 <artifactId>spring-boot-toolbox</artifactId>
-                <version>2.1.0</version>
+                <version>2.4.1</version>
             </dependency>
             <dependency>
                 <groupId>it.aboutbits</groupId>
                 <artifactId>archunit-toolbox</artifactId>
-                <version>1.0.0-RC1</version>
+                <version>1.1.0</version>
             </dependency>
         </dependencies>
     </dependencyManagement>
@@ -77,7 +78,7 @@
         <dependency>
             <groupId>net.datafaker</groupId>
             <artifactId>datafaker</artifactId>
-            <version>2.5.3</version>
+            <version>2.5.4</version>
         </dependency>
 
         <!-- https://mvnrepository.com/artifact/com.tngtech.archunit/archunit-junit5 -->
@@ -106,7 +107,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.14.1</version>
+                <version>3.15.0</version>
                 <configuration>
                     <source>${java.version}</source>
                     <target>${java.version}</target>
@@ -173,7 +174,7 @@
                     <dependency>
                         <groupId>com.puppycrawl.tools</groupId>
                         <artifactId>checkstyle</artifactId>
-                        <version>12.3.0</version>
+                        <version>13.4.0</version>
                     </dependency>
                     <dependency>
                         <groupId>it.aboutbits</groupId>
diff --git a/src/main/java/it/aboutbits/springboot/testing/testdata/FakerExtended.java b/src/main/java/it/aboutbits/springboot/testing/testdata/FakerExtended.java
new file mode 100644
index 0000000..a6d3018
--- /dev/null
+++ b/src/main/java/it/aboutbits/springboot/testing/testdata/FakerExtended.java
@@ -0,0 +1,113 @@
+package it.aboutbits.springboot.testing.testdata;
+
+import it.aboutbits.springboot.toolbox.type.ScaledBigDecimal;
+import it.aboutbits.springboot.toolbox.type.identity.EntityId;
+import net.datafaker.Faker;
+import net.datafaker.service.FakeValuesService;
+import net.datafaker.service.FakerContext;
+import net.datafaker.service.RandomService;
+import org.jspecify.annotations.NullMarked;
+
+import java.util.Locale;
+import java.util.Random;
+import java.util.function.Function;
+import java.util.function.LongFunction;
+
+@NullMarked
+public class FakerExtended extends Faker {
+    public FakerExtended() {
+        super();
+    }
+
+    public FakerExtended(Locale locale) {
+        super(locale);
+    }
+
+    public FakerExtended(Random random) {
+        super(random);
+    }
+
+    public FakerExtended(Locale locale, Random random) {
+        super(locale, random);
+    }
+
+    public FakerExtended(Locale locale, RandomService randomService) {
+        super(locale, randomService);
+    }
+
+    public FakerExtended(FakeValuesService fakeValuesService, FakerContext context) {
+        super(fakeValuesService, context);
+    }
+
+    public <T extends Enum<?>> T randomEnumValue(Class<T> enumClass) {
+        var values = enumClass.getEnumConstants();
+        if (values.length == 0) {
+            throw new IllegalArgumentException("Enum class must have at least one value");
+        }
+        return values[this.random().nextInt(values.length)];
+    }
+
+    public <T extends EntityId<Long>> T randomEntityId(LongFunction<T> constructor) {
+        return constructor.apply(
+                super.random().nextInt(9999999)
+        );
+    }
+
+    public <T extends EntityId<String>> T randomEntityId(Function<String, T> constructor) {
+        return constructor.apply(
+                super.internet().uuid()
+        );
+    }
+
+    public String unique(String value) {
+        return value + "_" + super.random().nextInt(9999999);
+    }
+
+    public RandomNumericRange numericRange() {
+        return new RandomNumericRange(
+                super.getFaker()
+        );
+    }
+
+    public static final class RandomNumericRange {
+        private final Faker parent;
+
+        private RandomNumericRange(Faker parent) {
+            this.parent = parent;
+        }
+
+        public NumericRange random() {
+            return random(-999999999, 999999999);
+        }
+
+        public NumericRange positive() {
+            return random(1, 999999999);
+        }
+
+        public NumericRange positiveOrZero() {
+            return random(0, 999999999);
+        }
+
+        public NumericRange negative() {
+            return random(-999999999, -1);
+        }
+
+        public NumericRange negativeOrZero() {
+            return random(-999999999, 0);
+        }
+
+        public NumericRange random(double min, double max) {
+            var lower = parent.random().nextDouble(min, max - 1);
+            var upper = parent.random().nextDouble(lower, max);
+
+            return new NumericRange(
+                    ScaledBigDecimal.valueOf(lower),
+                    ScaledBigDecimal.valueOf(upper)
+            );
+        }
+
+        public record NumericRange(ScaledBigDecimal lower, ScaledBigDecimal upper) {
+
+        }
+    }
+}
diff --git a/src/main/java/it/aboutbits/springboot/testing/testdata/base/FakerExtended.java b/src/main/java/it/aboutbits/springboot/testing/testdata/base/FakerExtended.java
index 3fbfb3c..d5a4315 100644
--- a/src/main/java/it/aboutbits/springboot/testing/testdata/base/FakerExtended.java
+++ b/src/main/java/it/aboutbits/springboot/testing/testdata/base/FakerExtended.java
@@ -13,6 +13,10 @@
 import java.util.function.Function;
 import java.util.function.LongFunction;
 
+/**
+ * @deprecated Moved. Use {@link it.aboutbits.springboot.testing.testdata.FakerExtended} instead. This class will be removed in a future release.
+ */
+@Deprecated(forRemoval = true)
 @NullMarked
 public class FakerExtended extends Faker {
     public FakerExtended() {
diff --git a/src/main/java/it/aboutbits/springboot/testing/testdata/base/ModifiableTestDataCreator.java b/src/main/java/it/aboutbits/springboot/testing/testdata/base/ModifiableTestDataCreator.java
index 208ec51..732004b 100644
--- a/src/main/java/it/aboutbits/springboot/testing/testdata/base/ModifiableTestDataCreator.java
+++ b/src/main/java/it/aboutbits/springboot/testing/testdata/base/ModifiableTestDataCreator.java
@@ -2,6 +2,7 @@
 
 import lombok.extern.slf4j.Slf4j;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -14,9 +15,6 @@
 @Slf4j
 @NullMarked
 public abstract class ModifiableTestDataCreator<CREATOR extends ModifiableTestDataCreator<CREATOR, ITEM, PARAMETER>, ITEM, PARAMETER> extends TestDataCreator<ITEM> {
-    @SuppressWarnings("unused")
-    protected static final FakerExtended FAKER = new FakerExtended();
-
     private boolean mutatorSet = false;
     private boolean mutatorCalled = false;
 
@@ -25,8 +23,8 @@ public abstract class ModifiableTestDataCreator<CREATOR extends ModifiableTestDa
         return parameter;
     };
 
-    protected ObjIntConsumer<ITEM> resultMutator = (_, _) -> {
-    };
+    @Nullable
+    protected ObjIntConsumer<ITEM> resultMutator = null;
 
     protected ModifiableTestDataCreator(int count) {
         super(count);
@@ -71,11 +69,15 @@ protected List<ITEM> create() {
         for (var index = 0; index < numberOfItems; index++) {
             var item = create(index);
 
-            resultMutator.accept(item, index);
+            if (resultMutator != null) {
+                resultMutator.accept(item, index);
 
-            result.add(
-                    saveMutation(item)
-            );
+                result.add(
+                        saveMutation(item)
+                );
+            } else {
+                result.add(item);
+            }
         }
 
         if (mutatorSet && !mutatorCalled) {
diff --git a/src/main/java/it/aboutbits/springboot/testing/testdata/base/TestDataCreator.java b/src/main/java/it/aboutbits/springboot/testing/testdata/base/TestDataCreator.java
index c5a810a..96287dd 100644
--- a/src/main/java/it/aboutbits/springboot/testing/testdata/base/TestDataCreator.java
+++ b/src/main/java/it/aboutbits/springboot/testing/testdata/base/TestDataCreator.java
@@ -1,5 +1,6 @@
 package it.aboutbits.springboot.testing.testdata.base;
 
+import it.aboutbits.springboot.testing.testdata.FakerExtended;
 import org.jspecify.annotations.NullMarked;
 
 import java.util.ArrayList;
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/core/ValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/core/ValueSource.java
index e9e7794..73fbf59 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/core/ValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/core/ValueSource.java
@@ -1,10 +1,11 @@
 package it.aboutbits.springboot.testing.validation.core;
 
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.stream.Stream;
 
 @NullMarked
 public interface ValueSource {
-    <T> Stream<T> values(Class<T> propertyClass, Object... args);
+    <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args);
 }
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/BiggerThanValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/BiggerThanValueSource.java
index c025aba..a52a70c 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/BiggerThanValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/BiggerThanValueSource.java
@@ -3,6 +3,7 @@
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import it.aboutbits.springboot.toolbox.type.ScaledBigDecimal;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -48,10 +49,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/BlankValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/BlankValueSource.java
index 8e3b96d..df91057 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/BlankValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/BlankValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -26,10 +27,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/EmptyValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/EmptyValueSource.java
index 1567f0c..72d6618 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/EmptyValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/EmptyValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -38,10 +39,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/FutureValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/FutureValueSource.java
index 82d5a72..9c1d716 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/FutureValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/FutureValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.time.Instant;
 import java.time.LocalDate;
@@ -43,10 +44,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/InertValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/InertValueSource.java
index f833467..bbbae90 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/InertValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/InertValueSource.java
@@ -2,13 +2,14 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.stream.Stream;
 
 @NullMarked
 public class InertValueSource implements ValueSource {
     @Override
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         return Stream.empty();
     }
 }
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/LessThanValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/LessThanValueSource.java
index 798f542..1ba951e 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/LessThanValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/LessThanValueSource.java
@@ -3,6 +3,7 @@
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import it.aboutbits.springboot.toolbox.type.ScaledBigDecimal;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -49,10 +50,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/LongerThanValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/LongerThanValueSource.java
index d4239dc..77ff0fa 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/LongerThanValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/LongerThanValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -25,10 +26,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/NullValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/NullValueSource.java
index 25cb35a..9a5fadc 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/NullValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/NullValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -19,10 +20,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         return Stream.of((T) null);
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/PastValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/PastValueSource.java
index 2642f83..9893488 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/PastValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/PastValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.time.Instant;
 import java.time.LocalDate;
@@ -43,10 +44,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/ShorterThanValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/ShorterThanValueSource.java
index 2ef0a08..ff56179 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/ShorterThanValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/ShorterThanValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -25,10 +26,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeGreaterThanValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeGreaterThanValueSource.java
index 001a4ae..90cc4d6 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeGreaterThanValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeGreaterThanValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.lang.reflect.Array;
 import java.util.ArrayList;
@@ -53,16 +54,16 @@ public static void registerType(Class<?> type, LongFunction<Stream<?>> source) {
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var value = (Long.valueOf((long) args[0]));
 
         if (propertyClass.isArray()) {
-            return (Stream<T>) arrayFunction(propertyClass, value);
+            return (Stream<@Nullable T>) arrayFunction(propertyClass, value);
         }
 
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(value);
+            return (Stream<@Nullable T>) sourceFunction.apply(value);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeLessThanValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeLessThanValueSource.java
index 36c96fc..e74af4d 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeLessThanValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/SizeLessThanValueSource.java
@@ -2,6 +2,7 @@
 
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.lang.reflect.Array;
 import java.util.ArrayList;
@@ -53,7 +54,7 @@ public static void registerType(Class<?> type, LongFunction<Stream<?>> source) {
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var value = (Long.valueOf((long) args[0]));
 
         if (value == 0) {
@@ -65,12 +66,12 @@ public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
         }
 
         if (propertyClass.isArray()) {
-            return (Stream<T>) arrayFunction(propertyClass, value);
+            return (Stream<@Nullable T>) arrayFunction(propertyClass, value);
         }
 
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(value);
+            return (Stream<@Nullable T>) sourceFunction.apply(value);
         }
 
         throw new IllegalArgumentException("Property class not supported!");
diff --git a/src/main/java/it/aboutbits/springboot/testing/validation/source/ZeroValueSource.java b/src/main/java/it/aboutbits/springboot/testing/validation/source/ZeroValueSource.java
index 016cbf4..0f27ad3 100644
--- a/src/main/java/it/aboutbits/springboot/testing/validation/source/ZeroValueSource.java
+++ b/src/main/java/it/aboutbits/springboot/testing/validation/source/ZeroValueSource.java
@@ -3,6 +3,7 @@
 import it.aboutbits.springboot.testing.validation.core.ValueSource;
 import it.aboutbits.springboot.toolbox.type.ScaledBigDecimal;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 import java.math.BigDecimal;
 import java.math.BigInteger;
@@ -46,10 +47,10 @@ public static void registerType(Class<?> type, Function<Object[], Stream<?>> sou
 
     @Override
     @SuppressWarnings("unchecked")
-    public <T> Stream<T> values(Class<T> propertyClass, Object... args) {
+    public <T> Stream<@Nullable T> values(Class<T> propertyClass, Object... args) {
         var sourceFunction = TYPE_SOURCES.get(propertyClass);
         if (sourceFunction != null) {
-            return (Stream<T>) sourceFunction.apply(args);
+            return (Stream<@Nullable T>) sourceFunction.apply(args);
         }
 
         throw new IllegalArgumentException("Property class not supported!");