private Tuple getTuple(String collectionName, String id, List<String> selectedColumns) {
EntityKey key = new EntityKey(
new EntityKeyMetadata( collectionName, new String[] { MongoDBDialect.ID_FIELDNAME } ),
new Object[] { id }
);
TupleContext tupleContext = new TupleContextImpl(
selectedColumns,
Collections.<String, AssociatedEntityKeyMetadata>emptyMap(),
Collections.<String, String>emptyMap(),
EmptyOptionsContext.INSTANCE
);