97 implement null handling with jspecify (#120)

* - Added jspecify to pom.xml
- @NullMarked to src/main/java/org/example
- Checked all files in example for handling null return values.

* - @NullMarked to src/main/java/org/example/config
- Checked all files for handling null return values

* - Added @NullMarked to src/main/java/org/example/filter package
- Checked all files for handling null return values

* - Added @NullMarked to src/main/java/org/example/http package
- Checked all files for handling null return values

* - Added @NullMarked to src/main/java/org/example/httpparser package
- Checked all files for handling null return values

* - Added @NullMarked to src/main/java/org/example/server package
- Checked all files for handling null return values

* - Added @NullMarked to src/test/java/org/example package
- Checked all files for handling null return values

* - Added @NullMarked to src/test/java/org/example/config package
- Checked ConfigLoaderTest for null handling

* - Added @NullMarked to src/test/java/org/example/filter package
- Checked all tests for null handling
- Marked body in HttpRequest parameters as nullable to satisfy tests in CompressionFilterTest.
- Marked ip parameters for normalizeIp, addBlockedIp and addAllowedIp to be Nullable since they work as intended but warnings need to be suppressed.
-Added @nullable to request parameter for doFilter in LocaleFilter since it is handled.

* - Added @NullMarked to src/test/java/org/example/http package
- Checked all tests for null handling
- Marked filename parameter in detectMimeType as Nullable since it's handled.

* - Added @NullMarked to src/test/java/org/example/httpparser package
- Checked all tests for null handling
- Marked "in" parameter for setReader in HttpParser as nullable since it is handled.

* - Added @NullMarked to src/test/java/org/example/server package
- Checked ConfigurableFilterPipelineTest for null handling
- Marked the routePatterns parameter in the FilterRegistration record in FilterRegistration.java since it is safely null handled.

* Applied suggested CodeRabbit fixes to Major Issues regarding null markings and null handling.

* CodeRabbit test went against intended outcome of test. Rollbacked change to SetReader in HttpParser

* - LocaleFilteR: Moved @nullable from doFilter request parameter to resolveLocale request parameter since resolveLocale does the actual null handling.
- Removed testParserThrowErrorWhenNull test since it is made redundant by jspecify null marking.

* - Fixed compilation errors.
- Tests and compilation run without issue on my local setup now.

Author: Martin-E-Karlsson

pom.xml

@@ -15,9 +15,7 @@
         <assertj.core.version>3.27.7</assertj.core.version>
         <mockito.version>5.21.0</mockito.version>
         <bucket4j.version>8.14.0</bucket4j.version>
-
     </properties>
-
     <dependencies>
         <dependency>
             <groupId>com.bucket4j</groupId>
@@ -70,14 +68,17 @@
             <artifactId>brotli4j</artifactId>
             <version>1.20.0</version>
         </dependency>
-
+        <dependency>
+            <groupId>org.jspecify</groupId>
+            <artifactId>jspecify</artifactId>
+            <version>1.0.0</version>
+        </dependency>
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
             <version>1.5.32</version>
             <scope>compile</scope>
         </dependency>
-
     </dependencies>
     <build>
         <plugins>

src/main/java/org/example/App.java

@@ -2,8 +2,8 @@
 
 import org.example.config.AppConfig;
 import org.example.config.ConfigLoader;
+import org.jspecify.annotations.Nullable;
 
-import java.net.Socket;
 import java.nio.file.Path;
 
 public class App {
@@ -30,7 +30,7 @@ static int resolvePort(String[] args, int configPort) {
         return validatePort(configPort, "configuration server.port");
     }
 
-    static Integer parsePortFromCli(String[] args) {
+    static @Nullable Integer parsePortFromCli(String[] args) {
         if (args == null) return null;
 
         for (int i = 0; i < args.length; i++) {

src/main/java/org/example/config/package-info.java

@@ -0,0 +1,4 @@
+@NullMarked
+package org.example.config;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/example/filter/CompressionFilter.java

@@ -4,6 +4,7 @@
 import org.example.http.HttpResponseBuilder;
 import org.example.httpparser.HttpRequest;
 import com.aayushatharva.brotli4j.encoder.Encoder;
+import org.jspecify.annotations.Nullable;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -186,7 +187,7 @@ private boolean shouldCompress(String contentType) {
                 baseType.startsWith("text/");
     }
 
-    private String getHeader(HttpRequest request, String headerName) {
+    private @Nullable String getHeader(HttpRequest request, String headerName) {
         Map<String, String> headers = request.getHeaders();
 
         String value = headers.get(headerName);

src/main/java/org/example/filter/IpFilter.java

@@ -3,6 +3,7 @@
 
 import org.example.http.HttpResponseBuilder;
 import org.example.httpparser.HttpRequest;
+import org.jspecify.annotations.Nullable;
 
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -84,22 +85,22 @@ private boolean isIpAllowed(String ip) {
      * @param ip the IP address
      * @return the trimmed IP address, or {@code null} if the input is {@code null}
      */
-    private String normalizeIp(String ip) {
+    private @Nullable String normalizeIp(@Nullable String ip) {
         return ip == null ? null : ip.trim();
     }
 
     public void setMode(FilterMode mode) {
         this.mode = mode;
     }
 
-    public void addBlockedIp(String ip) {
+    public void addBlockedIp(@Nullable String ip) {
         if (ip == null) {
             throw new IllegalArgumentException("IP address cannot be null");
         }
         blockedIps.add(normalizeIp(ip));
     }
 
-    public void addAllowedIp(String ip) {
+    public void addAllowedIp(@Nullable String ip) {
         if (ip == null) {
             throw new IllegalArgumentException("IP address cannot be null");
         }

src/main/java/org/example/filter/LocaleFilter.java

@@ -2,6 +2,7 @@
 
 import org.example.http.HttpResponseBuilder;
 import org.example.httpparser.HttpRequest;
+import org.jspecify.annotations.Nullable;
 
 import java.util.Map;
 
@@ -74,7 +75,7 @@ private String resolveLocale(HttpRequest request) {
      * <p>
      * If the cookie header is missing, blank, or malformed, returns null.
      */
-    private String extractLocaleFromCookie(HttpRequest request) {
+    private @Nullable String extractLocaleFromCookie(HttpRequest request) {
         Map<String, String> headers = request.getHeaders();
         if (headers == null) {
             return null;
@@ -111,7 +112,7 @@ private String extractLocaleFromCookie(HttpRequest request) {
      * If the header is missing, blank, or malformed, returns null.
      * The first language tag is used and any optional quality value (e.g., ";q=0.9") is stripped.
      */
-    private String extractLocaleFromHeader(HttpRequest request) {
+    private @Nullable String extractLocaleFromHeader(HttpRequest request) {
         Map<String, String> headers = request.getHeaders();
         if (headers == null) {
             return null;

src/main/java/org/example/filter/LocaleFilterWithCookie.java

@@ -0,0 +1,4 @@
+@NullMarked
+package org.example.filter;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/org/example/filter/package-info.java

@@ -1,5 +1,7 @@
 package org.example.http;
 
+import org.jspecify.annotations.Nullable;
+
 import java.util.Map;
 
 /**
@@ -56,7 +58,7 @@ private MimeTypeDetector() {
      */
 
 
-    public static String detectMimeType(String filename) {
+    public static String detectMimeType(@Nullable String filename) {
 
         String octet = "application/octet-stream";
 

src/main/java/org/example/http/MimeTypeDetector.java

@@ -0,0 +1,4 @@
+@NullMarked
+package org.example.http;
+
+import org.jspecify.annotations.NullMarked;