fix CI

Author: dimas-b

polaris-core/src/main/java/org/apache/polaris/core/persistence/EntityAlreadyExistsException.java

@@ -25,13 +25,14 @@
  * creation of a new entity; provides a member holding the conflicting entity.
  */
 public class EntityAlreadyExistsException extends RuntimeException {
-  private PolarisBaseEntity existingEntity;
+  private final PolarisBaseEntity existingEntity;
 
   /**
    * @param existingEntity The conflicting entity that caused creation to fail.
    */
   public EntityAlreadyExistsException(PolarisBaseEntity existingEntity) {
     super(message(existingEntity));
+    this.existingEntity = existingEntity;
   }
 
   public EntityAlreadyExistsException(PolarisBaseEntity existingEntity, Throwable cause) {