Fix #3177: use an instance of DatabaseTypeRegister when getting the C…

…lassLoader

flyway-core/src/main/java/org/flywaydb/core/internal/database/DatabaseTypeRegister.java

@@ -34,7 +34,7 @@
 
 public class DatabaseTypeRegister {
     private static final Log LOG = LogFactory.getLog(DatabaseTypeRegister.class);
-    public static ClassLoader classLoader = DatabaseTypeRegister.class.getClassLoader();
+    public static ClassLoader classLoader = new DatabaseTypeRegister().getClass().getClassLoader();
 
     private static final List<DatabaseType> registeredDatabaseTypes = new ArrayList<>();
     private static boolean hasRegisteredDatabaseTypes = false;