}
    }

    public void executeAfter(BuildStep stepToExecuteBefore) {
        if (!isSuccessorOf(stepToExecuteBefore)) {
            predecessors.add(stepToExecuteBefore);
            stepToExecuteBefore.successors.add(this);
        }
    }

    public void executeBefore(BuildStep stepToExecuteAfter) {
        stepToExecuteAfter.executeAfter(this);
    }

        firsts.stream()
                .filter(addNode -> !org.containsKey(addNode.name))
                .forEach(addNode -> lasts.forEach(orgNode -> addNode.executeAfter(orgNode)));
        add.forEach((name, node) -> org.merge(name, node, this::merge));
        return org;
    }

    private BuildStep merge(BuildStep node1, BuildStep node2) {