placeholder within placeholder

Please enable nested properties. Or in other words, resolve property values using other property values (and the context).

For example, if following are pulled from spring cloud configuration service:

nestL1 = [ L1 - ${nestL2} - L1 ]
nestL2 = [ L2 - ${nestL3} - L2 ]
nest = top - ${nestL1} - top

and context has:
nestL3 = [ L3 - deepest - L3 ]

Then config.get('nest') gives: "top - [ L1 - [ L2 - [ L3 - deepest - L3 ] - L2 ] - L1 ] - top"

Provide feedback