Failing rest calls

[ingorichtsmeier]

Introduce two new processes to test the different service task implemenation against a failing REST server.

The Folder WireMockService contains a java class that starts a wire mock server on port 8089 with some endpoints for:

• successful response
• delayed reponse for the impaitent (10 seconds)
• very long delay (10 minutes)
• resource not found (404)
• Server breakdown after 2 seconds

The first process (WireMockProcess) contains 4 service tasks in a row to test each type.

The second process (WireMockParallelProcess) contains 4 service tasks after a parallel gateway.

Java Delegate and External Task have special implementations to get the URL from a process variable.

In the start form you can choose, which of the 5 WireMock urls to call. All services calls the same url.

Then you can inspect in Cockpit what happens. If everything is OK, nothing to see. For server breakdown, you will see four incidents in the Parallel process.

[ingorichtsmeier]

As this pull request uses new artifacts, it doesn't harm the original story.

Some local expriments with starting 5 process instances with long delays showed that a careful setup with a real SQL Database (PostgresQL on docker?) is reqired to inspect the behavoir of the engine.

[ingorichtsmeier]

The default-number-of-retries is set to 1 to get the incidents after delays more quickly.

[CLAassistant]

All committers have signed the CLA.