@JoinFormula is a Hibernate-specific annotation that allows defining a join condition using a SQL formula expression instead of a simple foreign key column. For example,
@JoinFormula("COALESCE(targetRef, 0)") computes the join key dynamically rather than
referencing a stored column value.

Supporting @JoinFormula would require translating the raw MQL formula expression into an aggregation expression. This is non-trivial because the formula is an arbitrary MQL fragment that may contain functions, subqueries, or operators. 

Addressing TODO-HIBERNATE-182 is in the scope of this ticket.