InverseRelationShadowVariable (OptaPlanner distribution 8.10.0.Final API)

```
@Target({METHOD,FIELD})
@Retention(RUNTIME)
public @interface InverseRelationShadowVariable
```
Specifies that a bean property (or a field) is the inverse of a PlanningVariable, which implies it's a shadow variable.
It is specified on a getter of a java bean property (or a field) of a PlanningEntity class.

Required Element Summary

Required Elements
Modifier and Type	Required Element	Description
`String`	`sourceVariableName`	In a bidirectional relationship, the shadow side (= the follower side) uses this property (and nothing else) to declare for which `PlanningVariable` (= the leader side) it is a shadow.

- Element Detail
  - sourceVariableName
```
String sourceVariableName
```
    In a bidirectional relationship, the shadow side (= the follower side) uses this property (and nothing else) to declare for which PlanningVariable (= the leader side) it is a shadow.
    Both sides of a bidirectional relationship should be consistent: if A points to B, then B must point to A.
    When the Solver changes a genuine variable, it adjusts the shadow variable accordingly. In practice, the Solver ignores shadow variables (except for consistency housekeeping).
    
    Returns:
    
    the variable property name on the opposite end of this bidirectional relationship