private boolean updateRootNodes(Function function) {
		GTreeNode root = incomingTree.getModelRoot();
		// root might be a "PendingRootNode"
		if (root instanceof CallNode) {
			CallNode callNode = (CallNode) root;
			Function nodeFunction = callNode.getRemoteFunction();
			if (nodeFunction.equals(function)) {
				reloadUpdateManager.update();
				return true;
			}
		}

		return false;
	}
A variable used to restrict open-ended operations, like expanding all nodes or filtering.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/calltree/CallTreeProvider.java