private boolean isAlias(Expression<?> expr) {
        return expr instanceof Operation && ((Operation<?>) expr).getOperator() == Ops.ALIAS;
    }
{@code NativeSQLSerializer} extends {@link SQLSerializer} to extract referenced entity paths and change
some serialization formats

@author tiwe
querydsl-jpa/src/main/java/com/querydsl/jpa/NativeSQLSerializer.java