code: private void initialiseInstanceVariables() {
  		backing = new HashMap<>();
  		booleanBacking = new HashSet<>();
  		locations = new HashMap<>();
  
  		// subContextCache is updated on the fly so ensure no concurrent modification.
  		subcontextCache = Collections.synchronizedMap(new HashMap());
  		runtimeProperties = new IncludeProperties("Runtime: added at runtime");
  	}
docs: This method initialises most of the instance variables.