Access step execution context data from job xml / JSL

job xml elements should be able to reference runtime values inside step execution context. The referencing job xml element will be late-binding. For example,

<property name="rate" value="#{stepExecutionContext['rate']}" />

• which job xml elements or attributes within a step need to support this feature? Do we limit it to artifact-level properties only?
• do we want to support transitive reference, i.e., other job properties referencing a property having stepExecutionContext expression?
• how to perform late binding? similar to partitionPlan properties
• where to store these data inside StepContextImpl? need to add a new field for that?