complexity of this algorithm?

HierarchyParser.java

public TreeNode parseHiearchy(List<OrganizationUnit> organizationUnits) {
    HashMap<String, OrganizationUnit> divisions = new HashMap<>();
    HashMap<String, List<OrganizationUnit>> departments = new HashMap<>();
    HashMap<String, List<OrganizationUnit>> jobs = new HashMap<>();

    for (OrganizationUnit organizationUnit : organizationUnits) {
        switch (organizationUnit.getOrganizationUnitType()) {
            case DIVISION: {
                divisions.put(organizationUnit.getPrefix(), organizationUnit);
                break;
            }
            case DEPARTMENT: {
                departments.computeIfAbsent(getPrefixAbove(organizationUnit.getPrefix()), k -> new ArrayList<>())
                        .add(organizationUnit);
                break;
            }
            case JOB: {
                jobs.computeIfAbsent(getPrefixAbove(organizationUnit.getPrefix()), k -> new ArrayList<>())
                        .add(organizationUnit);
                break;
            }
        }
    }

    TreeNode root = new TreeNode();
    root.isRoot = true;

    for (String divisionPrefix : divisions.keySet()) {
        TreeNode divisionNode = new TreeNode(divisions.get(divisionPrefix));
        root.addChild(divisionNode);

        for (OrganizationUnit department : departments.get(divisionPrefix)) {
            TreeNode departmentNode = new TreeNode(department);
            divisionNode.addChild(departmentNode);

            for (OrganizationUnit job : jobs.get(department.getPrefix())) {
                TreeNode jobNode = new TreeNode(job);
                departmentNode.addChild(jobNode);
            }
        }
    }

    return root;
}