Refactor serialization adapter retrieval by version (#1066)

This PR prepares for #1063 by moving the `initializeAdapter` declaration
from `FixSerializationConfig` to `SerializationVersionAdapter`. This
change ensures that version-specific serializations are handled directly
by `SerializationVersionAdapter`, which will simplify test modifications
in #1063.

This transition also aligns with a clearer design, as
`SerializationVersionAdapter` should be responsible for computing the
appropriate adapter for each new version. This approach will help us
maintain version updates within `SerializationVersionAdapter` while
keeping `FixSerializationConfig` unchanged.

I'm uncertain if maintaining backward compatibility is necessary in the
long term. If it's not needed, we can consider removing it in the
future. For now, however, this PR is required to keep #1063 concise.

nullaway/src/main/java/com/uber/nullaway/fixserialization/FixSerializationConfig.java

@@ -24,8 +24,6 @@
 
 import com.google.common.base.Preconditions;
 import com.uber.nullaway.fixserialization.adapters.SerializationAdapter;
-import com.uber.nullaway.fixserialization.adapters.SerializationV1Adapter;
-import com.uber.nullaway.fixserialization.adapters.SerializationV3Adapter;
 import com.uber.nullaway.fixserialization.out.SuggestedNullableFixInfo;
 import java.io.IOException;
 import java.nio.file.Files;
@@ -86,7 +84,9 @@ public FixSerializationConfig(
     this.suggestEnclosing = suggestEnclosing;
     this.fieldInitInfoEnabled = fieldInitInfoEnabled;
     this.outputDirectory = outputDirectory;
-    serializer = new Serializer(this, initializeAdapter(SerializationAdapter.LATEST_VERSION));
+    serializer =
+        new Serializer(
+            this, SerializationAdapter.getAdapterForVersion(SerializationAdapter.LATEST_VERSION));
   }
 
   /**
@@ -126,32 +126,11 @@ public FixSerializationConfig(String configFilePath, int serializationVersion) {
         XMLUtil.getValueFromAttribute(
                 document, "/serialization/fieldInitInfo", "active", Boolean.class)
             .orElse(false);
-    SerializationAdapter serializationAdapter = initializeAdapter(serializationVersion);
+    SerializationAdapter serializationAdapter =
+        SerializationAdapter.getAdapterForVersion(serializationVersion);
     serializer = new Serializer(this, serializationAdapter);
   }
 
-  /**
-   * Initializes NullAway serialization adapter according to the requested serialization version.
-   */
-  private SerializationAdapter initializeAdapter(int version) {
-    switch (version) {
-      case 1:
-        return new SerializationV1Adapter();
-      case 2:
-        throw new RuntimeException(
-            "Serialization version v2 is skipped and was used for an alpha version of the auto-annotator tool. Please use version 3 instead.");
-      case 3:
-        return new SerializationV3Adapter();
-      default:
-        throw new RuntimeException(
-            "Unrecognized NullAway serialization version: "
-                + version
-                + ". Supported versions: 1 to "
-                + SerializationAdapter.LATEST_VERSION
-                + ".");
-    }
-  }
-
   public @Nullable Serializer getSerializer() {
     return serializer;
   }

nullaway/src/main/java/com/uber/nullaway/fixserialization/adapters/SerializationAdapter.java

@@ -71,4 +71,29 @@ public interface SerializationAdapter {
    * @return The serialized method symbol.
    */
   String serializeMethodSignature(Symbol.MethodSymbol methodSymbol);
+
+  /**
+   * Gets the adapter for the given version number.
+   *
+   * @param version Version number of the adapter.
+   * @return Adapter for the given version.
+   */
+  static SerializationAdapter getAdapterForVersion(int version) {
+    switch (version) {
+      case 1:
+        return new SerializationV1Adapter();
+      case 2:
+        throw new RuntimeException(
+            "Serialization version v2 is skipped and was used for an alpha version of the auto-annotator tool. Please use version 3 instead.");
+      case 3:
+        return new SerializationV3Adapter();
+      default:
+        throw new RuntimeException(
+            "Unrecognized NullAway serialization version: "
+                + version
+                + ". Supported versions: 1 to "
+                + SerializationAdapter.LATEST_VERSION
+                + ".");
+    }
+  }
 }