diff --git a/pom.xml b/pom.xml
index 00b72a6..a0f87c3 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,13 +5,14 @@
     <parent>
         <groupId>ch.fritteli</groupId>
         <artifactId>fritteli-build-parent</artifactId>
-        <version>5.1.0</version>
+        <version>6.1.0</version>
     </parent>
 
     <groupId>ch.fritteli.a-maze-r</groupId>
     <artifactId>maze-server</artifactId>
     <version>0.2.1-SNAPSHOT</version>
 
+    <name>A-Maze-R Server</name>
     <description>The A-Maze-R server, offering a REST endpoint to access the Maze Generator.</description>
     <url>https://manuel.friedli.info/maze.html</url>
     <inceptionYear>2022</inceptionYear>
@@ -55,9 +56,9 @@
     </distributionManagement>
 
     <properties>
-        <maze-generator.version>0.3.0</maze-generator.version>
-        <maven-site-plugin.version>4.0.0-M8</maven-site-plugin.version>
-        <undertow.version>2.3.18.Final</undertow.version>
+        <maze-generator.version>0.4.0</maze-generator.version>
+        <maven-site-plugin.version>4.0.0-M16</maven-site-plugin.version>
+        <undertow.version>2.3.22.Final</undertow.version>
     </properties>
 
     <dependencies>
@@ -75,8 +76,8 @@
             <artifactId>lombok</artifactId>
         </dependency>
         <dependency>
-            <groupId>org.jetbrains</groupId>
-            <artifactId>annotations</artifactId>
+            <groupId>org.jspecify</groupId>
+            <artifactId>jspecify</artifactId>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
@@ -98,7 +99,6 @@
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
-            <scope>test</scope>
         </dependency>
     </dependencies>
 
diff --git a/src/main/java/ch/fritteli/maze/server/Algorithm.java b/src/main/java/ch/fritteli/maze/server/Algorithm.java
index 6d4f29f..1cd5d95 100644
--- a/src/main/java/ch/fritteli/maze/server/Algorithm.java
+++ b/src/main/java/ch/fritteli/maze/server/Algorithm.java
@@ -8,8 +8,8 @@ import io.vavr.collection.List;
 import io.vavr.collection.Stream;
 import io.vavr.control.Option;
 import lombok.Getter;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 
 import java.util.function.Function;
 
@@ -17,20 +17,20 @@ public enum Algorithm {
     RANDOM_DEPTH_FIRST(RandomDepthFirst::new, "random", "random-depth-first"),
     WILSON(Wilson::new, "wilson");
 
-    @NotNull
+    @NonNull
     private final Function<Maze, MazeGeneratorAlgorithm> creator;
 
     @Getter
-    @NotNull
+    @NonNull
     private final List<String> names;
 
-    Algorithm(@NotNull final Function<Maze, MazeGeneratorAlgorithm> creator,
-              @NotNull final String... names) {
+    Algorithm(@NonNull final Function<Maze, MazeGeneratorAlgorithm> creator,
+              @NonNull final String... names) {
         this.creator = creator;
         this.names = List.of(names);
     }
 
-    @NotNull
+    @NonNull
     public static Option<Algorithm> ofString(@Nullable final String name) {
         return Option.of(name)
                 .map(String::toLowerCase)
@@ -38,8 +38,8 @@ public enum Algorithm {
                         .find(algorithm -> algorithm.getNames().contains(nameLC)));
     }
 
-    @NotNull
-    public MazeGeneratorAlgorithm createAlgorithm(@NotNull final Maze maze) {
+    @NonNull
+    public MazeGeneratorAlgorithm createAlgorithm(@NonNull final Maze maze) {
         return this.creator.apply(maze);
     }
 }
diff --git a/src/main/java/ch/fritteli/maze/server/ConfigurationException.java b/src/main/java/ch/fritteli/maze/server/ConfigurationException.java
index 1159634..d1d659a 100644
--- a/src/main/java/ch/fritteli/maze/server/ConfigurationException.java
+++ b/src/main/java/ch/fritteli/maze/server/ConfigurationException.java
@@ -1,6 +1,6 @@
 package ch.fritteli.maze.server;
 
-import org.jetbrains.annotations.Nullable;
+import org.jspecify.annotations.Nullable;
 
 public class ConfigurationException extends RuntimeException {
     public ConfigurationException(@Nullable final String message) {
diff --git a/src/main/java/ch/fritteli/maze/server/InvalidRequestParameterException.java b/src/main/java/ch/fritteli/maze/server/InvalidRequestParameterException.java
index a103796..dff5ff0 100644
--- a/src/main/java/ch/fritteli/maze/server/InvalidRequestParameterException.java
+++ b/src/main/java/ch/fritteli/maze/server/InvalidRequestParameterException.java
@@ -1,9 +1,9 @@
 package ch.fritteli.maze.server;
 
-import org.wildfly.common.annotation.NotNull;
+import org.jspecify.annotations.NonNull;
 
 public class InvalidRequestParameterException extends RuntimeException {
-    public InvalidRequestParameterException(@NotNull final String s) {
+    public InvalidRequestParameterException(@NonNull final String s) {
         super(s);
     }
 }
diff --git a/src/main/java/ch/fritteli/maze/server/Main.java b/src/main/java/ch/fritteli/maze/server/Main.java
index 687fa4d..9781817 100644
--- a/src/main/java/ch/fritteli/maze/server/Main.java
+++ b/src/main/java/ch/fritteli/maze/server/Main.java
@@ -7,7 +7,7 @@ import lombok.extern.slf4j.Slf4j;
 @UtilityClass
 public class Main {
 
-    public static void main(String[] args) {
+    static void main() {
         MazeServer.createAndStartServer()
                 .onFailure(e -> log.error("Failed to create server. Stopping.", e));
     }
diff --git a/src/main/java/ch/fritteli/maze/server/MazeServer.java b/src/main/java/ch/fritteli/maze/server/MazeServer.java
index f864975..4a22f68 100644
--- a/src/main/java/ch/fritteli/maze/server/MazeServer.java
+++ b/src/main/java/ch/fritteli/maze/server/MazeServer.java
@@ -9,17 +9,17 @@ import io.undertow.Undertow;
 import io.undertow.server.RoutingHandler;
 import io.vavr.control.Try;
 import lombok.extern.slf4j.Slf4j;
-import org.wildfly.common.annotation.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.net.InetSocketAddress;
 
 @Slf4j
 public class MazeServer {
 
-    @NotNull
+    @NonNull
     private final Undertow undertow;
 
-    private MazeServer(@NotNull final ServerConfig config) {
+    private MazeServer(@NonNull final ServerConfig config) {
         final String hostAddress = config.address().getHostAddress();
         final int port = config.port();
         log.info("Starting Server at http://{}:{}/", hostAddress, port);
@@ -36,14 +36,14 @@ public class MazeServer {
                 .build();
     }
 
-    @NotNull
+    @NonNull
     public static Try<MazeServer> createAndStartServer() {
         return Try.of(ServerConfig::init)
                 .flatMapTry(MazeServer::createAndStartServer);
     }
 
-    @NotNull
-    public static Try<MazeServer> createAndStartServer(@NotNull final ServerConfig config) {
+    @NonNull
+    public static Try<MazeServer> createAndStartServer(@NonNull final ServerConfig config) {
         return Try.of(() -> new MazeServer(config))
                 .peek(MazeServer::start);
     }
diff --git a/src/main/java/ch/fritteli/maze/server/OutputType.java b/src/main/java/ch/fritteli/maze/server/OutputType.java
index ad8d25d..3c637e9 100644
--- a/src/main/java/ch/fritteli/maze/server/OutputType.java
+++ b/src/main/java/ch/fritteli/maze/server/OutputType.java
@@ -12,8 +12,8 @@ import io.vavr.collection.List;
 import io.vavr.collection.Stream;
 import io.vavr.control.Option;
 import lombok.Getter;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 
 import java.nio.charset.StandardCharsets;
 import java.util.function.Function;
@@ -75,24 +75,24 @@ public enum OutputType {
             "3",
             "binaryv3");
     @Getter
-    @NotNull
+    @NonNull
     private final String contentType;
     @Getter
-    @NotNull
+    @NonNull
     private final String fileExtension;
-    @NotNull
-    private final Function<Maze, byte[]> render;
+    @NonNull
+    private final Function<@NonNull Maze, byte @NonNull []> render;
     @Getter
     private final boolean attachment;
     @Getter
-    @NotNull
+    @NonNull
     private final List<String> names;
 
-    OutputType(@NotNull final String contentType,
-               @NotNull final String fileExtension,
-               @NotNull final Function<Maze, byte[]> render,
+    OutputType(@NonNull final String contentType,
+               @NonNull final String fileExtension,
+               @NonNull final Function<Maze, byte[]> render,
                final boolean attachment,
-               @NotNull final String... names) {
+               @NonNull final String... names) {
         this.contentType = contentType;
         this.render = render;
         this.fileExtension = fileExtension;
@@ -100,7 +100,7 @@ public enum OutputType {
         this.names = List.of(names);
     }
 
-    @NotNull
+    @NonNull
     public static Option<OutputType> ofString(@Nullable final String name) {
         return Option.of(name)
                 .map(String::toLowerCase)
@@ -109,14 +109,14 @@ public enum OutputType {
 
     }
 
-    @NotNull
+    @NonNull
     @Override
     public String toString() {
         return this.names.last();
     }
 
-    @NotNull
-    public byte[] render(@NotNull final Maze maze) {
+    @NonNull
+    public byte[] render(@NonNull final Maze maze) {
         return this.render.apply(maze);
     }
 }
diff --git a/src/main/java/ch/fritteli/maze/server/ServerConfig.java b/src/main/java/ch/fritteli/maze/server/ServerConfig.java
index 401fd6d..645589b 100644
--- a/src/main/java/ch/fritteli/maze/server/ServerConfig.java
+++ b/src/main/java/ch/fritteli/maze/server/ServerConfig.java
@@ -3,25 +3,25 @@ package ch.fritteli.maze.server;
 import io.vavr.control.Option;
 import io.vavr.control.Try;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 
 import java.net.InetAddress;
 
 @Slf4j
-public record ServerConfig(@NotNull InetAddress address,
+public record ServerConfig(@NonNull InetAddress address,
                            int port,
-                           @NotNull Option<Integer> maxMazeHeight,
-                           @NotNull Option<Integer> maxMazeWidth) {
+                           @NonNull Option<Integer> maxMazeHeight,
+                           @NonNull Option<Integer> maxMazeWidth) {
     public static final String SYSPROP_HOST = "fritteli.maze.server.host";
     public static final String SYSPROP_PORT = "fritteli.maze.server.port";
     public static final String SYSPROP_MAX_MAZE_HEIGHT = "fritteli.maze.maxheight";
     public static final String SYSPROP_MAX_MAZE_WIDTH = "fritteli.maze.maxwidth";
 
-    public ServerConfig(@NotNull final InetAddress address,
+    public ServerConfig(@NonNull final InetAddress address,
                         final int port,
-                        @NotNull final Option<Integer> maxMazeHeight,
-                        @NotNull final Option<Integer> maxMazeWidth) {
+                        @NonNull final Option<Integer> maxMazeHeight,
+                        @NonNull final Option<Integer> maxMazeWidth) {
         this.address = address;
         this.port = validatePort(port);
         this.maxMazeHeight = validateDimension(maxMazeHeight, "height");
@@ -31,13 +31,13 @@ public record ServerConfig(@NotNull InetAddress address,
 
     public ServerConfig(@Nullable final String address,
                         final int port,
-                        @NotNull final Option<Integer> maxMazeHeight,
-                        @NotNull final Option<Integer> maxMazeWidth)
+                        @NonNull final Option<Integer> maxMazeHeight,
+                        @NonNull final Option<Integer> maxMazeWidth)
             throws ConfigurationException {
         this(validateAddress(address), port, maxMazeHeight, maxMazeWidth);
     }
 
-    @NotNull
+    @NonNull
     public static ServerConfig init() throws ConfigurationException {
         final String host = System.getProperty(SYSPROP_HOST);
         final String portString = System.getProperty(SYSPROP_PORT);
@@ -49,7 +49,7 @@ public record ServerConfig(@NotNull InetAddress address,
         return new ServerConfig(host, port, maxMazeHeight, maxMazeWidth);
     }
 
-    @NotNull
+    @NonNull
     private static InetAddress validateAddress(@Nullable final String address) throws ConfigurationException {
         return Try.of(() -> InetAddress.getByName(address))
                 .getOrElseThrow(cause -> new ConfigurationException(
@@ -77,9 +77,9 @@ public record ServerConfig(@NotNull InetAddress address,
                 ));
     }
 
-    @NotNull
-    private static Option<Integer> validateDimension(@NotNull final Option<Integer> dimension,
-                                                     @NotNull final String identifier) {
+    @NonNull
+    private static Option<Integer> validateDimension(@NonNull final Option<Integer> dimension,
+                                                     @NonNull final String identifier) {
         if (dimension.exists(d -> d <= 1)) {
             throw new ConfigurationException("Maximum %s must be greater than 1: %s"
                     .formatted(identifier, dimension.get()));
@@ -88,8 +88,8 @@ public record ServerConfig(@NotNull InetAddress address,
     }
 
     private static Option<Integer> validateDimension(@Nullable final String dimensionString,
-                                                     @NotNull final String identifier,
-                                                     @NotNull final String syspropName) {
+                                                     @NonNull final String identifier,
+                                                     @NonNull final String syspropName) {
         if (dimensionString == null) {
             log.info("No maximum {} configured; using default (unlimited).", identifier);
             return Option.none();
diff --git a/src/main/java/ch/fritteli/maze/server/handler/AbstractHttpHandler.java b/src/main/java/ch/fritteli/maze/server/handler/AbstractHttpHandler.java
index f129b5f..c96a668 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/AbstractHttpHandler.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/AbstractHttpHandler.java
@@ -4,7 +4,7 @@ import io.undertow.server.HttpHandler;
 import io.undertow.server.HttpServerExchange;
 import io.undertow.util.StatusCodes;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 import org.slf4j.MDC;
 
 import java.time.Instant;
@@ -14,9 +14,9 @@ import java.util.UUID;
 @Slf4j
 public abstract class AbstractHttpHandler implements HttpHandler {
     @Override
-    public final void handleRequest(@NotNull final HttpServerExchange exchange) {
+    public final void handleRequest(@NonNull final HttpServerExchange exchange) {
         final Instant start = Instant.now();
-        try (final MDC.MDCCloseable closeable = MDC.putCloseable("correlationId", UUID.randomUUID().toString())) {
+        try (final MDC.MDCCloseable _ = MDC.putCloseable("correlationId", UUID.randomUUID().toString())) {
 
             if (exchange.isInIoThread()) {
                 log.debug("Dispatching request");
@@ -35,5 +35,5 @@ public abstract class AbstractHttpHandler implements HttpHandler {
         }
     }
 
-    protected abstract void handle(@NotNull final HttpServerExchange exchange) throws Exception;
+    protected abstract void handle(@NonNull final HttpServerExchange exchange) throws Exception;
 }
diff --git a/src/main/java/ch/fritteli/maze/server/handler/CreateHandler.java b/src/main/java/ch/fritteli/maze/server/handler/CreateHandler.java
index 8eb8f0f..f082dbc 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/CreateHandler.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/CreateHandler.java
@@ -10,7 +10,7 @@ import io.undertow.util.StatusCodes;
 import io.vavr.control.Option;
 import io.vavr.control.Try;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 import org.slf4j.MDC;
 
 import java.nio.ByteBuffer;
@@ -23,18 +23,18 @@ import java.util.Map;
 public class CreateHandler extends AbstractHttpHandler {
 
     public static final String PATH_TEMPLATE = "/create/{output}";
-    @NotNull
+    @NonNull
     private final Option<Integer> maxHeight;
-    @NotNull
+    @NonNull
     private final Option<Integer> maxWidth;
 
-    public CreateHandler(@NotNull final Option<Integer> maxHeight, @NotNull final Option<Integer> maxWidth) {
+    public CreateHandler(@NonNull final Option<Integer> maxHeight, @NonNull final Option<Integer> maxWidth) {
         this.maxHeight = maxHeight;
         this.maxWidth = maxWidth;
     }
 
     @Override
-    protected void handle(@NotNull final HttpServerExchange exchange) {
+    protected void handle(@NonNull final HttpServerExchange exchange) {
         final Instant start = Instant.now();
         log.debug("Handling create request");
         this.createMazeFromRequestParameters(exchange.getQueryParameters())
@@ -65,6 +65,7 @@ public class CreateHandler extends AbstractHttpHandler {
                     final long durationMillis = start.until(Instant.now(), ChronoUnit.MILLIS);
                     exchange.getResponseHeaders()
                             .put(Headers.CONTENT_TYPE, outputType.getContentType())
+                            .put(HttpString.tryFromString("Access-Control-Allow-Origin"), "*")
                             .put(HttpString.tryFromString("X-Maze-ID"), String.valueOf(maze.getRandomSeed()))
                             .put(HttpString.tryFromString("X-Maze-Width"), String.valueOf(maze.getWidth()))
                             .put(HttpString.tryFromString("X-Maze-Height"), String.valueOf(maze.getHeight()))
@@ -84,7 +85,7 @@ public class CreateHandler extends AbstractHttpHandler {
                 });
     }
 
-    @NotNull
+    @NonNull
     private Try<ParametersToMazeExtractor.GeneratedMaze> createMazeFromRequestParameters(final Map<String, Deque<String>> queryParameters) {
         return new ParametersToMazeExtractor(queryParameters, this.maxHeight, this.maxWidth).createMaze();
     }
diff --git a/src/main/java/ch/fritteli/maze/server/handler/ParametersToMazeExtractor.java b/src/main/java/ch/fritteli/maze/server/handler/ParametersToMazeExtractor.java
index 93f9964..d844be1 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/ParametersToMazeExtractor.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/ParametersToMazeExtractor.java
@@ -10,7 +10,7 @@ import io.vavr.collection.Stream;
 import io.vavr.control.Option;
 import io.vavr.control.Try;
 import lombok.RequiredArgsConstructor;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.util.Deque;
 import java.util.Map;
@@ -19,14 +19,14 @@ import java.util.Random;
 @RequiredArgsConstructor
 class ParametersToMazeExtractor {
 
-    @NotNull
+    @NonNull
     private final Map<String, Deque<String>> queryParameters;
-    @NotNull
+    @NonNull
     private final Option<Integer> maxHeight;
-    @NotNull
+    @NonNull
     private final Option<Integer> maxWidth;
 
-    @NotNull
+    @NonNull
     Try<GeneratedMaze> createMaze() {
         final Option<OutputType> output = getParameterValue(RequestParameter.OUTPUT);
         final Option<Integer> width = getParameterValue(RequestParameter.WIDTH);
@@ -87,11 +87,11 @@ class ParametersToMazeExtractor {
         });
     }
 
-    @NotNull
-    private <T> Option<T> getParameterValue(@NotNull final RequestParameter parameter) {
+    @NonNull
+    private <T> Option<T> getParameterValue(@NonNull final RequestParameter parameter) {
         return parameter.getParameterValue(this.queryParameters);
     }
 
-    public record GeneratedMaze(@NotNull Maze maze, @NotNull OutputType outputType) {
+    public record GeneratedMaze(@NonNull Maze maze, @NonNull OutputType outputType) {
     }
 }
diff --git a/src/main/java/ch/fritteli/maze/server/handler/RenderV1Handler.java b/src/main/java/ch/fritteli/maze/server/handler/RenderV1Handler.java
index 82165df..47aa5ca 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/RenderV1Handler.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/RenderV1Handler.java
@@ -8,7 +8,7 @@ import io.undertow.util.HeaderValues;
 import io.undertow.util.Headers;
 import io.undertow.util.StatusCodes;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.nio.ByteBuffer;
 
@@ -18,7 +18,7 @@ public class RenderV1Handler extends AbstractHttpHandler {
     public static final String PATH_TEMPLATE = "/render/v1/{output}";
 
     @Override
-    public void handle(@NotNull final HttpServerExchange exchange) {
+    public void handle(@NonNull final HttpServerExchange exchange) {
         log.debug("Handling render request");
 
         if (exchange.isInIoThread()) {
@@ -47,8 +47,8 @@ public class RenderV1Handler extends AbstractHttpHandler {
         });
     }
 
-    @NotNull
-    private OutputType getOutputType(@NotNull final HttpServerExchange httpServerExchange) {
+    @NonNull
+    private OutputType getOutputType(@NonNull final HttpServerExchange httpServerExchange) {
         return RequestParameter.OUTPUT.<OutputType>getParameterValue(httpServerExchange.getQueryParameters())
                 .getOrElse(() -> {
                     final HeaderValues accept = httpServerExchange.getRequestHeaders().get(Headers.ACCEPT);
diff --git a/src/main/java/ch/fritteli/maze/server/handler/RenderV2Handler.java b/src/main/java/ch/fritteli/maze/server/handler/RenderV2Handler.java
index bd4a856..9d97787 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/RenderV2Handler.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/RenderV2Handler.java
@@ -8,7 +8,7 @@ import io.undertow.util.HeaderValues;
 import io.undertow.util.Headers;
 import io.undertow.util.StatusCodes;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.nio.ByteBuffer;
 
@@ -18,7 +18,7 @@ public class RenderV2Handler extends AbstractHttpHandler {
     public static final String PATH_TEMPLATE = "/render/v2/{output}";
 
     @Override
-    public void handle(@NotNull final HttpServerExchange exchange) {
+    public void handle(@NonNull final HttpServerExchange exchange) {
         log.debug("Handling render request");
 
         if (exchange.isInIoThread()) {
@@ -47,8 +47,8 @@ public class RenderV2Handler extends AbstractHttpHandler {
         });
     }
 
-    @NotNull
-    private OutputType getOutputType(@NotNull final HttpServerExchange httpServerExchange) {
+    @NonNull
+    private OutputType getOutputType(@NonNull final HttpServerExchange httpServerExchange) {
         return RequestParameter.OUTPUT.<OutputType>getParameterValue(httpServerExchange.getQueryParameters())
                 .getOrElse(() -> {
                     final HeaderValues accept = httpServerExchange.getRequestHeaders().get(Headers.ACCEPT);
diff --git a/src/main/java/ch/fritteli/maze/server/handler/RenderV3Handler.java b/src/main/java/ch/fritteli/maze/server/handler/RenderV3Handler.java
index 0b8987e..f83b0ae 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/RenderV3Handler.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/RenderV3Handler.java
@@ -8,7 +8,7 @@ import io.undertow.util.HeaderValues;
 import io.undertow.util.Headers;
 import io.undertow.util.StatusCodes;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.nio.ByteBuffer;
 
@@ -18,7 +18,7 @@ public class RenderV3Handler extends AbstractHttpHandler {
     public static final String PATH_TEMPLATE = "/render/v3/{output}";
 
     @Override
-    public void handle(@NotNull final HttpServerExchange exchange) {
+    public void handle(@NonNull final HttpServerExchange exchange) {
         log.debug("Handling render request");
 
         if (exchange.isInIoThread()) {
@@ -47,8 +47,8 @@ public class RenderV3Handler extends AbstractHttpHandler {
         });
     }
 
-    @NotNull
-    private OutputType getOutputType(@NotNull final HttpServerExchange httpServerExchange) {
+    @NonNull
+    private OutputType getOutputType(@NonNull final HttpServerExchange httpServerExchange) {
         return RequestParameter.OUTPUT.<OutputType>getParameterValue(httpServerExchange.getQueryParameters())
                 .getOrElse(() -> {
                     final HeaderValues accept = httpServerExchange.getRequestHeaders().get(Headers.ACCEPT);
diff --git a/src/main/java/ch/fritteli/maze/server/handler/RenderVxHandler.java b/src/main/java/ch/fritteli/maze/server/handler/RenderVxHandler.java
index 5db984f..8b09118 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/RenderVxHandler.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/RenderVxHandler.java
@@ -12,7 +12,7 @@ import io.undertow.util.HeaderValues;
 import io.undertow.util.Headers;
 import io.undertow.util.StatusCodes;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.nio.ByteBuffer;
 
@@ -21,7 +21,7 @@ public class RenderVxHandler implements HttpHandler {
     public static final String PATH_TEMPLATE = "/render/dyn/{output}";
 
     @Override
-    public void handleRequest(@NotNull final HttpServerExchange exchange) {
+    public void handleRequest(@NonNull final HttpServerExchange exchange) {
         log.debug("Handling render request");
 
         if (exchange.isInIoThread()) {
@@ -55,8 +55,8 @@ public class RenderVxHandler implements HttpHandler {
         });
     }
 
-    @NotNull
-    private Version getVersion(@NotNull final byte[] bytes) throws IllegalArgumentException {
+    @NonNull
+    private Version getVersion(final byte @NonNull [] bytes) throws IllegalArgumentException {
         if (bytes.length < 3) {
             throw new IllegalArgumentException("Invalid input: too short");
         }
@@ -73,8 +73,8 @@ public class RenderVxHandler implements HttpHandler {
         }
     }
 
-    @NotNull
-    private OutputType getOutputType(@NotNull final HttpServerExchange httpServerExchange) {
+    @NonNull
+    private OutputType getOutputType(@NonNull final HttpServerExchange httpServerExchange) {
         return RequestParameter.OUTPUT.<OutputType>getParameterValue(httpServerExchange.getQueryParameters())
                 .getOrElse(() -> {
                     final HeaderValues accept = httpServerExchange.getRequestHeaders().get(Headers.ACCEPT);
@@ -86,6 +86,6 @@ public class RenderVxHandler implements HttpHandler {
     }
 
     private enum Version {
-        V1, V2, V3;
+        V1, V2, V3
     }
 }
diff --git a/src/main/java/ch/fritteli/maze/server/handler/RequestParameter.java b/src/main/java/ch/fritteli/maze/server/handler/RequestParameter.java
index 5cdd893..b1d39c2 100644
--- a/src/main/java/ch/fritteli/maze/server/handler/RequestParameter.java
+++ b/src/main/java/ch/fritteli/maze/server/handler/RequestParameter.java
@@ -11,7 +11,7 @@ import io.vavr.control.Option;
 import io.vavr.control.Try;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
-import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NonNull;
 
 import java.util.Deque;
 import java.util.Map;
@@ -25,7 +25,7 @@ enum RequestParameter {
     HEIGHT(p -> Try.of(() -> Integer.parseInt(p))
             .toOption()
             .onEmpty(() -> log.debug("Unparseable value for parameter 'height': '{}'", p)), "h", "height"),
-    ID(p -> Try.of(() -> Long.parseLong(p))
+    ID(p -> Try.of(() -> Long.parseUnsignedLong(p, 16))
             .toOption()
             .onEmpty(() -> log.debug("Unparseable value for parameter 'id': '{}'", p)), "i", "id"),
     OUTPUT(p -> OutputType.ofString(p)
@@ -48,24 +48,24 @@ enum RequestParameter {
             .onEmpty(() -> log.debug("Unparseable value for parameter 'end': '{}'", p)), "e", "end"),
     ALGORITHM(p -> Algorithm.ofString(p)
             .onEmpty(() -> log.debug("Unparseable value for parameter 'algorithm': '{}'", p)), "a", "algorithm");
-    @NotNull
+    @NonNull
     private final Function<String, Option<?>> extractor;
     @Getter
-    @NotNull
+    @NonNull
     private final Set<String> names;
 
-    RequestParameter(@NotNull final Function<String, Option<?>> extractor, @NotNull final String... names) {
+    RequestParameter(@NonNull final Function<String, Option<?>> extractor, @NonNull final String... names) {
         this.extractor = extractor;
         this.names = HashSet.of(names);
     }
 
-    @NotNull
-    Option<?> extractParameterValue(@NotNull final String parameter) {
+    @NonNull
+    Option<?> extractParameterValue(@NonNull final String parameter) {
         return this.extractor.apply(parameter);
     }
 
-    @NotNull
-    public <T> Option<T> getParameterValue(@NotNull final Map<String, Deque<String>> queryParameters) {
+    @NonNull
+    public <T> Option<T> getParameterValue(@NonNull final Map<String, Deque<String>> queryParameters) {
         return (Option<T>) HashMap.ofAll(queryParameters)
                 .filterKeys(this.names::contains)
                 .flatMap(Tuple2::_2)