How to wait for a workflow state to complete

Similar to https://github.com/indeedeng/iwf/wiki/How-to-wait-for-a-workflow-to-complete

External application and make a blocking API call to wait for a state execution to complete.

To wait for a workflow state execution to complete, the stateExecutionId must be provided as waitForCompletionStateExecutionIds in the startWorkflowOptions.

Then use client.waitForStateExecution(stateClass) API to wait for the completion.

See this example in Java integ test.

By default, the API will wait For the first execution. But a state could have multiple executions, and you may need to wait for the 2nd,3rd or other executions of the state.In that case, you can use client.waitForStateExecution(stateClass, stateExecutionNumber) to wait for the certain one by number.

stateExecutionNumber is a sequential number maintained by the server. iWF also allow you to specify a key instead of the number. This is helpful in some cases to have full control. See this PR for how to use this feature.

Note1: the state that is waited for, must be registered to the workflowOptions on startWorkflow API. This is a limitation until https://github.com/indeedeng/iwf/issues/349

Note2: that currently, this feature cannot be used with reusing workflowId for more than one executions. See https://github.com/indeedeng/iwf/issues/404 for improvement which require a new field in Temporal API: https://github.com/temporalio/temporal/issues/6348