Add JSpecify and NullAway (#27)

Author: scordio

pom.xml

@@ -58,6 +58,11 @@
       <artifactId>jimfs</artifactId>
       <version>${jimfs.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.jspecify</groupId>
+      <artifactId>jspecify</artifactId>
+      <version>1.0.0</version>
+    </dependency>
     <!-- Provided -->
     <dependency>
       <groupId>org.junit.jupiter</groupId>
@@ -107,6 +112,7 @@
                 -Xplugin:ErrorProne
                 -Xep:ImmutableEnumChecker:OFF
                 -Xep:SameNameButDifferent:OFF
+                -XepOpt:NullAway:OnlyNullMarked
               </compilerArg>
             </compilerArgs>
             <annotationProcessorPaths>
@@ -115,6 +121,11 @@
                 <artifactId>error_prone_core</artifactId>
                 <version>2.38.0</version>
               </path>
+              <path>
+                <groupId>com.uber.nullaway</groupId>
+                <artifactId>nullaway</artifactId>
+                <version>0.12.7</version>
+              </path>
             </annotationProcessorPaths>
             <failOnWarning>true</failOnWarning>
           </configuration>
@@ -129,9 +140,11 @@
           <artifactId>maven-javadoc-plugin</artifactId>
           <version>3.11.2</version>
           <configuration>
+            <additionalOptions>--link-modularity-mismatch=info</additionalOptions> <!-- https://github.com/jspecify/jspecify/issues/712 -->
             <failOnWarnings>true</failOnWarnings>
             <links>
               <link>https://javadoc.io/static/com.google.jimfs/jimfs/${jimfs.version}/</link>
+              <link>https://jspecify.dev/docs/api/</link>
               <link>https://junit.org/junit5/docs/${junit-jupiter.version}/api/</link>
             </links>
             <release>9</release>
@@ -229,6 +242,7 @@
               <excludes>
                 <exclude>module-info.java</exclude>
               </excludes>
+              <failOnWarning>false</failOnWarning> <!-- https://github.com/jspecify/jspecify/issues/302 -->
             </configuration>
           </execution>
         </executions>

src/main/java/io/github/scordio/jimfs/junit/jupiter/JimfsTempDirFactory.java

@@ -24,6 +24,7 @@
 import java.util.Locale;
 import java.util.Optional;
 import java.util.function.Supplier;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.extension.AnnotatedElementContext;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.api.io.TempDirFactory;
@@ -59,7 +60,7 @@ public final class JimfsTempDirFactory implements TempDirFactory {
 
   private static final String DEFAULT_PREFIX = "junit-";
 
-  private FileSystem fileSystem;
+  private @Nullable FileSystem fileSystem;
 
   /** Create a new {@code JimfsTempDirFactory} instance. */
   public JimfsTempDirFactory() {}
@@ -102,6 +103,9 @@ private static boolean isNotDefaultConfiguration(JimfsTempDir.Configuration valu
   /** {@inheritDoc} */
   @Override
   public void close() throws IOException {
-    fileSystem.close();
+    if (fileSystem != null) {
+      fileSystem.close();
+      fileSystem = null;
+    }
   }
 }

src/main/java/io/github/scordio/jimfs/junit/jupiter/package-info.java

@@ -18,4 +18,7 @@
  * JUnit Jupiter {@link org.junit.jupiter.api.io.TempDir} extension based on {@link
  * com.google.common.jimfs.Jimfs}.
  */
+@NullMarked
 package io.github.scordio.jimfs.junit.jupiter;
+
+import org.jspecify.annotations.NullMarked;

src/main/java/module-info.java

@@ -20,6 +20,7 @@
  */
 @SuppressWarnings({"requires-automatic", "requires-transitive-automatic"})
 module io.github.scordio.jimfs.junit.jupiter {
+  requires static org.jspecify;
   requires transitive com.google.common.jimfs;
   requires org.junit.jupiter.api;