ETL Static Analysis - Detect equivalent elements property access

[arcanefoam]

When using ETL, it is fine to use the equivalents operation to retrieve target elements created by other rules. However, as soon as you access any attribute in a target element retrieved by equivalents, you are relying on a specific rule execution order, i.e. you are not only expecting the rule to have created the element, but also that the body of the rule to be executed and the element's attributes/relations to be set. This expectation can not be fulfilled by the two-pass execution strategy of ETL.
The static analyzer could flag this as a warning and recommend that the rule accessing the attributes should be annotated as lazy.