Workflow-Core: How to implement decision step and invoke from api

[dbandyop005]

Scenario: A product is created. A notification is sent to approver for approval. If approved/rejected it updates the product status in db. Trying to achieve this using Workflow-Core in .net application.

//Below is the builder:
public void Build(IWorkflowBuilder builder)
{
builder
.StartWith < **CreateProductStep * *> ()
.WaitFor("ApprovedProduct", (data, context) => data.ProductId)
.Then < **ApproveRejectStep * *> ();
}

//These are the workflow steps:
public class CreateProductStep : StepBody
{
public override ExecutionResult Run(IStepExecutionContext context)
{
var data = context.Workflow.Data as MyData;

    Console.WriteLine($"Product created {data.ProductId} {data.IsApproved}");
    return ExecutionResult.Next();
}

}

public class ApproveRejectStep : StepBody
{
public override ExecutionResult Run(IStepExecutionContext context)
{
var data = context.Workflow.Data as MyData;

    Console.WriteLine($"Product updated {data.ProductId} {data.IsApproved}");
    return ExecutionResult.Next();
}

}
//The Controller:

[HttpPost("addproduct")]
public async Task AddProduct([FromBody] MyData product)
{
var workflowId = await _workflowHost.StartWorkflow("ProductWorkflow1", product);
return Ok(new { WorkflowId = workflowId, Message = "Product added and workflow started." });
}
[HttpPost("approve-reject-product")]
public async Task ApproveRejectProduct([FromBody] MyData product)
{
await _workflowHost.PublishEvent("ApprovedProduct", product.ProductId, product);

return Ok(new { Message = $"Product {product.IsApproved}" });

}

Expecting the WaitFor to get the context of the first step:CreateProductStep and pass it to the next step:ApproveRejectStep. Which is not happening. What am I missing here. How can I achieve passing the context of the previous flow to the next waitfor step and invoke via api.