Bugfix: NullPointerException at CacheIndexMetadata.getField() (#2110)

PROBLEM
=======
NullPointerException raising at CacheIndexMetadata.getField() while EntityManager initialising.

CAUSE
=======
Entity metadata XML file contains tag <cache-index><column-name>SOMENAME</column-name></cache-index>.
XML Deserializer call CacheIndexMetadata default constructor. ORMetadata.m_project field stay none initialised.
Call of CacheIndexMetadata.getField() throw to exception.

SOLVING
=======
Set ORMetadata.m_project value after XML deserialization.

Signed-off-by: Radek Felcman <radek.felcman@oracle.com>

jpa/org.eclipse.persistence.jpa/src/main/java/org/eclipse/persistence/internal/jpa/metadata/accessors/classes/MappedSuperclassAccessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1998, 2021 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2024 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
@@ -1016,6 +1016,7 @@ protected void processCacheIndexes() {
         }
 
         for (CacheIndexMetadata indexMetadata : m_cacheIndexes) {
+            indexMetadata.setProject(getProject());
             indexMetadata.process(getDescriptor(), null);
         }
     }