[BUG] Validate that all step IDs are unique

[amitgalitz]

What is the bug?

Currently we are allowed to create a template where we have duplicate step IDs throughout the steps. It would be beneficial to ensure these step IDs are unique so they can be used to identify different steps, especially in the resources created section.

This can be crucial for users wanting to know which step they listed corresponds to the created resource id.

Solution:

We can add validation to make sure all step_id's are unique, this can be done by adding the step_id to a set and make sure we don't have duplicates.

[dbwiddis]

The topological sorter uses a map internally when sorting the nodes:

flow-framework/src/main/java/org/opensearch/flowframework/workflow/WorkflowProcessSorter.java

Line 71 in 0edf9cb

Map<String, ProcessNode> idToNodeMap = new HashMap<>();

So while there is a bug, it's far worse than just the resources created. It totally messes up the logic of the sorting, combining edges and other nastiness.

Easy fix is to check if the key exists here before putting in the map.

flow-framework/src/main/java/org/opensearch/flowframework/workflow/WorkflowProcessSorter.java

Line 92 in 0edf9cb

idToNodeMap.put(processNode.id(), processNode);

[dbwiddis]

Actually, that won't work, the ids are already unique in the topological sorting from here:

flow-framework/src/main/java/org/opensearch/flowframework/workflow/WorkflowProcessSorter.java

Line 161 in 0edf9cb

Set<String> nodeIds = workflowNodes.stream().map(n -> n.id()).collect(Collectors.toSet());

So the fix is to compare the size of that set to the size of workflowNodes.