Add equals and hashCode to ArrayPropertyGetter

Author: mtdowling

rulesengine/src/main/java/software/amazon/smithy/java/rulesengine/ArrayPropertyGetter.java

@@ -5,10 +5,14 @@
 
 package software.amazon.smithy.java.rulesengine;
 
+import java.util.Arrays;
+
 /**
  * Lightweight PropertyGetter backed by an interleaved value/key array.
  * Layout: [value0, key0, value1, key1, ...]. Keys are at odd indices.
  * More efficient than Map for small fixed-key lookups (linear scan beats hashing for ~4 entries).
+ *
+ * <p>Equality is value-based on the contents of {@code data} so callers can use instances as cache keys.
  */
 record ArrayPropertyGetter(Object[] data) implements PropertyGetter {
     @Override
@@ -20,4 +24,14 @@ public Object getProperty(String name) {
         }
         return null;
     }
+
+    @Override
+    public boolean equals(Object o) {
+        return o instanceof ArrayPropertyGetter other && Arrays.equals(data, other.data);
+    }
+
+    @Override
+    public int hashCode() {
+        return Arrays.hashCode(data);
+    }
 }