Advanced LINQ join scenarios often throw exceptions

[gliljas]

Examples:

• Nesting two LeftJoins

Unit test added in #2737

[bahusoid]

Nesting two LeftJoins

Isn't it a join on subquery? Join on subquery requires first hql support (see #2551)

[gliljas]

In the most general sense, it is a join on a subquery, but in some scenarios it could be resolved into a chained join.

Anyway, I just added it here for completeness. It's a minor issue, for me.

Oh, how I wish LINQ support wasn't built on HQL.