private void validate() {
		if (overlaySet == null) {
			overlaySet =
				overlayRegionSupplier != null ? overlayRegionSupplier.getOverlayAddressSet(this)
						: new AddressSet();
			if (overlaySet == null) {
				overlaySet = new AddressSet();
			}
		}
	}
@param key DB record key
@param overlayName current overlay name
@param baseSpace base address space (type should be restricted as neccessary by caller)
@param unique assigned unique ID
@param overlayRegionSupplier callback handler which supplies the defined address set 
for a specified overlay address space. 
@param factory used to determine a suitable ordered overlay ordered-key used for
{@link #equals(Object)} and {@link #compareTo(AddressSpace)}.
@throws DuplicateNameException if specified name duplicates an existing address space name
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/ProgramOverlayAddressSpace.java