Getting Issue Type Scheme and Workflow Scheme for JIRA project using REST API

This is what you want. /rest/projectconfig/1/workflowscheme/{projectIdOrKey}

Latest Jira documentation provides information about the APIs which can be used to fetch details for issuetype scheme and workflow scheme. Below are the APIs which can be used for the same,

1. Fetching Issue type Scheme for a project Issuetype Scheme API

Rest URL:GET https://your-domain.atlassian.com/rest/api/2/issuetypescheme/project?projectId={projectId}'

Sample Response:

{
    "maxResults": 100,
    "startAt": 0,
    "total": 3,
    "isLast": true,
    "values": [
        {
            "issueTypeScheme": {
                "id": "10000",
                "name": "Default Issue Type Scheme",
                "description": "Default issue type scheme is the list of global issue types. All newly created issue types will automatically be added to this scheme.",
                "defaultIssueTypeId": "10003",
                "isDefault": true
            },
            "projectIds": [
                "10000",
                "10001"
            ]
        }
    ]
}

2. Fetching workflow scheme configured for a project Workflow Scheme API

REST URl: GET https://your-domain.atlassian.com/rest/api/2/workflowscheme/{id}

Sample Response:

{
  "id": 101010,
  "name": "Example workflow scheme",
  "description": "The description of the example workflow scheme.",
  "defaultWorkflow": "jira",
  "issueTypeMappings": {
    "10000": "scrum workflow",
    "10001": "builds workflow"
  },
  "draft": false,
  "self": "https://your-domain.atlassian.net/rest/api/2/workflowscheme/101010"
}

As far as I am aware you can get the correct XML or JSON response from the REST API:

/rest/api/2/project/{projectIdOrKey}.  

Then if you want to find out the information about the workflowscheme you can do this programmatically by using the following information.

If you have an issue that you want to use then you can use it to get the workflowscheme id by doing this this:

ComponentAccessor.getWorkflowSchemeManager().getWorkflowScheme(issue.getProject()).get("id");

Then once you get the id of the workflow scheme e.g. 10, you then can get the scheme generic value as follows:

GernericValue scheme = ComponentAccessor.getWorkflowSchemeManager().getScheme(10);

Now that you have the scheme you then can get all of the workflows that are referenced in the scheme by doing this:

Collection<JiraWorkflow> workflows = ComponentAccessor.getWorkflowManager().getWorkflowsFromScheme(scheme);

Then if you want to get one workflow you will have to use:

workflows.iterator().next():

Also note, that workflows are identified by their name in JIRA as there are no id's in JiraWorkflow.

So that would be the approach I would use if I wanted to find out the workflowscheme information so I could use the id to then use the REST API:

But the main reason that you might not be able to find a workflowscheme is because it is not present in the JIRA's Issue.

Using this HTTP and inputting it into "Postman" as a get request will return all the JSON information.

Using this https://jira.atlassian.com/browse/JRA-25121/project/23 will return all the information for that project. Then using this REST API:

/rest/api/2/workflowscheme/{id}

Using this HTTP get request https://jira.atlassian.com/browse/JRA-25121/workflow/45 will get you the returned XML or JSON workflow information too.