AFSocketAddress: Prevent false-positive "mutable object" warnings

kohlschuetter · kohlschuetter · commit a6dda2580a9a · 2023-09-15T10:57:33.000+02:00
When passing AFSocketAddress as constructor arguments, spotbugs may erroneously claim that we expose class internals due to the address being mutable. In fact, all mutable fields of AFSocketAddress are only mutable so we can support deserialization, and are not modifiable otherwise. Add @immutable, and suppress some corresponding warnings in code.
diff --git a/junixsocket-common/src/main/java/org/newsclub/net/unix/AFSocketAddress.java b/junixsocket-common/src/main/java/org/newsclub/net/unix/AFSocketAddress.java
@@ -42,11 +42,15 @@
 import org.eclipse.jdt.annotation.NonNull;
 import org.eclipse.jdt.annotation.Nullable;
 
+import com.google.errorprone.annotations.Immutable;
+import com.kohlschutter.annotations.compiletime.SuppressFBWarnings;
+
 /**
  * Some {@link SocketAddress} that is supported by junixsocket, such as {@link AFUNIXSocketAddress}.
  *
  * @author Christian Kohlschütter
  */
+@Immutable
 @SuppressWarnings({"PMD.CouplingBetweenObjects", "PMD.CyclomaticComplexity"})
 public abstract class AFSocketAddress extends InetSocketAddress {
   private static final long serialVersionUID = 1L; // do not change!
@@ -91,12 +95,15 @@ protected ByteBuffer initialValue() {
    * Some byte-level representation of this address, which can only be converted to a native
    * representation in combination with the domain ID.
    */
+  @SuppressFBWarnings("JCIP_FIELD_ISNT_FINAL_IN_IMMUTABLE_CLASS")
   private byte[] bytes;
 
   /**
    * An {@link InetAddress}-wrapped representation of this address. Only created upon demand.
    */
-  private InetAddress inetAddress = null;
+  @SuppressFBWarnings("JCIP_FIELD_ISNT_FINAL_IN_IMMUTABLE_CLASS") // only modified during
+                                                                  // construction/deserialization
+  private InetAddress inetAddress = null; // derived from bytes
 
   /**
    * The system-native representation of this address, or {@code null}.
