1) Empty array causes NPE in Spring Cloud config

2) Spring cloud config does not log the exception.

We use config-service. Spring Cloud version 2.1 used to work well. When we updated Spring Cloud version 2.2, it stopped working.

I use Spring profile native and fetch configuration from local file on dev machine (not from git repository).

This is an example of a configuration file in spring config. python-service.yml

resources:
  - resource1
  - resource2

newResources: []

The problem is caused by newResources: []. However, it worked in Spring Cloud v 2.1. Examples, I used curl and Postman. HTTP http://localhost:8888/python-service/dev Accept: application/vnd.spring-cloud.config-server.v2+json returns fail result 1).

{
    "timestamp": "2020-04-24T08:38:19.803+0000",
    "status": 500,
    "error": "Internal Server Error",
    "message": "Could not construct context for config=python-service profile=dev label=null includeOrigin=true; nested exception is java.lang.NullPointerException",
    "path": "/python-service/dev"
}

Next, without the Accept header, it works. HTTP http://localhost:8888/python-service/dev Returns success result 2).

{
    "name": "python-service",
    "profiles": [
        "dev"
    ],
    "label": null,
    "version": null,
    "state": null,
    "propertySources": [
        {
            "name": "file:/configuration/python-service.yml",
            "source": {
                "resources[0]": "resource1",
                "resources[1]": "resource2",
                "newResources": ""
            }
        }
    ]
}

By the way, why `"newResources": ""` is an empty String, if it was an array.

However, the header Accept: application/vnd.spring-cloud.config-server.v2+json is sent by Spring Cloud config client (unfortunately, I had to debug it!). In the version 2.1, there is Accept: application/json

As you see, different value for `Accept` header.

Next, when I down-graded Spring Cloud 2.1 It works http://localhost:8888/python-service/dev Accept: application/json Success result 2).

When I use Spring Cloud config-service version 2.2 and remove empty array from python-service.yml on local machine, it works as well. http://localhost:8888/python-service/dev returns success result 3)

{
    "name": "python-service",
    "profiles": [
        "dev"
    ],
    "label": null,
    "version": null,
    "state": null,
    "propertySources": [
        {
            "name": "file:/configuration/python-service.yml",
            "source": {
                "resources[0]": {
                    "value": "resource1",
                    "origin": "2:5"
                },
                "resources[1]": {
                    "value": "resource2",
                    "origin": "3:5"
                }
            }
        }
    ]
}

I do not know what origin: "3.5" is though. Please, advise.

How to support empty array in the configuration. It breaks our services.

Links https://github.com/spring-cloud/spring-cloud-config/issues/866 https://github.com/spring-projects/spring-boot/issues/12965 https://github.com/spring-projects/spring-framework/issues/21310

Comment From: spencergibb

Please provide the stack trace