@Override
	public List<GTreeNode> generateChildren(TaskMonitor monitor) throws CancelledException {

		FunctionSignatureFieldLocation location =
			new FunctionSignatureFieldLocation(program, functionAddress);

		Set<Address> addresses = ReferenceUtils.getReferenceAddresses(location, monitor);
		LazyMap<Function, List<GTreeNode>> nodesByFunction =
			LazyMap.lazyMap(new HashMap<>(), k -> new ArrayList<>());
		FunctionManager functionManager = program.getFunctionManager();
		for (Address fromAddress : addresses) {
			monitor.checkCancelled();
			Function callerFunction = functionManager.getFunctionContaining(fromAddress);
			if (callerFunction == null) {
				continue;
			}

			InSliceNode node = new InSliceNode(program, callerFunction, fromAddress,
				filterDuplicates, filterDepth);
			addNode(nodesByFunction, node);
		}

		List<GTreeNode> children =
			nodesByFunction.values()
					.stream()
					.flatMap(list -> list.stream())
					.collect(Collectors.toList());
		Collections.sort(children, new CallNodeComparator());

		return children;
	}
These are nodes that are in the left tree and below the InSliceRootNode. That is a little deceptive; see below.

<p>
A location in the call tree that is ABOVE or has an in-path to base node (node of interest / root).
e.g., the top in-node is the program entry point in many cases.
Ghidra/Features/DecompilerDependent/src/main/java/ghidra/app/plugin/core/decompiler/taint/slicetree/InSliceNode.java