protected LegacyDbConnProvider createConnectionProvider(final DataSource dataSource) {
        return new DataSourceImpl(dataSource);
    }
Configures anything related to persistence, e.g. transaction management, the
entity manager factory, data sources.
<p>
This does not extend {@link stroom.db.util.AbstractDataSourceProviderModule} as the core migrations
are special and need to happen first before all the other migrations. {@link ForceLegacyMigration} is
used to achieve this by making all other datasource providers depend on {@link ForceLegacyMigration}.
stroom-legacy/stroom-legacy-db-migration/src/main/java/stroom/legacy/db/LegacyDbModule.java