Input does not start after ContentPack ReST creation

## Expected Behavior
When I create a contentPack using graylog ReST API and apply it in a new and empty environment, the input should start without error

## Current Behavior
When I create a contentPack using graylog ReST API and apply it in a new and empty environment, the input start fails. The log tell me that the port is already in use (it is a new installation). Restarting the application the input become magically green

## Possible Solution
Maybe something change in ReST input creation with content pack and UI one

## Steps to Reproduce (for bugs)

1. Create a stream and an input
2. Export it using content pack
3. Import content pack using rest client
4. The input does not start and the log describe the error (port already in use

## Context

## Your Environment
ContentPack creation and installation work fine but I have this problem on the input view


Looking the Graylog log I see:


If I create another input using the UI it works fine

I'm sure that the 12201 is not used. If I restart the application it become green


* Graylog Version: Applicance: Graylog 4.0.7+c3e766c on graylog (Private Build 1.8.0_292 on Linux 4.15.0-142-generic)
* Java Version: openjdk version "1.8.0_292"
* Elasticsearch Version: 7.10.2
* MongoDB Version: 4.0.24
* Operating System: ubuntu 18.04
* Browser version: