I have dug a bit more on this - my original checking code was wrong

The problem (I think) is that the J2E classloader doesn't seem to recognise a "folder" as a resource.

String checkFile = "database_migration/V1__my_db.sql";    // specific SQL file
System.out.println("Datafile ["+checkFile+"]");
URL resource = Thread.currentThread().getContextClassLoader().getResource(checkFile);
if (resource != null) {
    System.out.println("RESOURCE FILE ["+checkFile+"] URL["+resource.toExternalForm()+"]");   
}
else {
    System.out.println("RESOURCE URL returned ["+(resource != null ? resource.toString() : "is null")+"]");                   
}

Returns (I note the j2e: reference in URL)

RESOURCE FILE [database_migration/V1__my_db.sql] URL[j2e:libs/MyDBUtiliity.jar!database_migration/V1__my_db.sql]

However with just a folder as

String checkFile = "database_migration";    // just folder with versioned SQL files

Returns

RESOURCE URL returned [is null]

Whereas in normal java environment this returns

RESOURCE FILE [database_migration] URL[file:/C:/Users/david/dev/MyApplication/target/classes/database_migration]

My problem is that Flyway seems to only work at folder level

Flyway flyway = new Flyway();
flyway.setClassLoader(Thread.currentThread().getContextClassLoader());
flyway.setDataSource(ds);
flyway.setLocations(migrations);  // String[] with multiple folders with versioned SQL files
flyway.setCallbacks(new MyFlywayCallback());
flyway.migrate();

I'm looking for a work-around in Flyway - but wondered if you could confirm J2E ClassLoader support for folders as resource?

Edit:

Flyway is a BoxFuse product (rather than Google as I indicated above) - here is their info on Database Migrations <https://flywaydb.org/documentation/migrations#versioned-migrations>. 

I have got the option to use "filesystem:" working - rather than "classpath:",  but that would leave SQL files, which define the application database, exposed and getting the classpath approach working is my strong preference.

Thanks

David