HHH-15046: test for db2z & db2i initalization error

both errors ocure because private property "version" is used
through the super-constructor before being intialized.

hibernate-core/src/test/java/org/hibernate/orm/test/dialect/DB2iDialectInitTestCase.java

@@ -0,0 +1,23 @@
+package org.hibernate.orm.test.dialect;
+
+import org.hibernate.dialect.DB2iDialect;
+import org.hibernate.testing.RequiresDialect;
+import org.hibernate.testing.TestForIssue;
+import org.junit.Test;
+
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * @author Onno Goczol
+ */
+@TestForIssue(jiraKey = "HHH-15046")
+@RequiresDialect(DB2iDialect.class)
+public class DB2iDialectInitTestCase {
+
+    @Test
+    public void testInitUniqueDelegate() {
+        final var db2iDialect = new DB2iDialect();
+        assertNotNull(db2iDialect);
+    }
+
+}

hibernate-core/src/test/java/org/hibernate/orm/test/dialect/DB2zDialectInitTestCase.java

@@ -0,0 +1,32 @@
+package org.hibernate.orm.test.dialect;
+
+import org.hibernate.dialect.DB2zDialect;
+import org.hibernate.testing.RequiresDialect;
+import org.hibernate.testing.TestForIssue;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.hibernate.type.SqlTypes.TIMESTAMP_WITH_TIMEZONE;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * @author Onno Goczol
+ */
+@TestForIssue(jiraKey = "HHH-15046")
+@RequiresDialect(DB2zDialect.class)
+public class DB2zDialectInitTestCase {
+
+    static class DB2zDialectWithExplicitTimezoneSupport extends DB2zDialect {
+        @Override
+        protected List<Integer> getSupportedJdbcTypeCodes() {
+            return List.of(TIMESTAMP_WITH_TIMEZONE);
+        }
+    }
+
+    @Test
+    public void testInitWithTimezoneSupport() {
+        final var db2zDialect = new DB2zDialectWithExplicitTimezoneSupport();
+        assertNotNull(db2zDialect);
+    }
+}