Revert "XD-1650 Remove unused property"

This reverts commit 2de6d88c1e273ccd747de65ab7a7f7db3d89dddc.
XD-1650 Remove unused property
XD-1650 Use StandardEvaluationContext instead of EvaluationContext

- Change constructors to use StandardEvaluationContext directly.
- Casting from EvaluationContext to StandardEvaluationContext
  now happens earlier in a factory which gets it
  from IntegrationEvaluationContextAware.
- We now fail in MessageExpressionMethods if evaluation
  context is null instead of creating it manually.