private void markStale() {
		isStale = true;

		// Deleting this when stale allows us to free the memory.  This is useful, since it
		// is possible that once marked stale, we may never have another request for this data
		// again.
		dataTypeList = Collections.emptyList();
		categoryPathList = Collections.emptyList();
	}
Returns a list of the unique Category Paths ({@link CategoryPath}) as utilized by the 
data types open in the current tool.  

@return a list of the {@link CategoryPath} associated with the data types open in the 
current tool.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/archive/DataTypeIndexer.java