Fix SmallRye Health OpenAPI definitions

[frne]

The quarkus-smallrye-health extension exposes an openapi definition for the health endpoints it provides. The current implementation exposes a wrong schema that doesn't reflect the actual structure of the returned JSON.

Problem Statement

Since the openapi schema does not match the implementation, a JSON object is returned that does not adhere to the interface documentation. Especially in code generation use cases, this leads to errors that are difficult to debug / understand for implementers.

Current schema

The schema exposed by the current implementation renders to something similar to:

{
  "data": {},
  "name": "string",
  "status": "DOWN"
}

Issues with the current schema:

• The health response object only has statusand checks properties (source)
• Properties name and data will not be used in the top-level response (source)
• The checks property in the top-level response schema is missing completely (source, source)
• The checks entries have a defined object schema of name, status and data, that is currently not reflected in the schema (source).
• The exposed schema should comply with Eclipse Microprofile Health

New schema

The schema after the fix, renders to:

{
  "status": "UP",
  "checks": [
    {
      "status": "UP",
      "data": {},
      "name": "string"
    }
  ]
}

This fixes the exposed schema to actually match the JSON structure returned by the endpoints. Additionally, the filter implementation (io.quarkus.smallrye.health.deployment.HealthOpenAPIFilter) has been refactored to use a more fluid and readable schema definition instead of the many private methods.

The PR reflects a minimally functional implementation. Please provide input regarding missing features or tests.

[xstefank]

LGTM, Thanks for a very detailed PR. Great work.

[frne]

I was unaware of the format validation, sorry. Fixing it anytime soon...

[gsmet]

Thanks for your PR!