this was living outside the properties key...

excludes is causing issues with AJV, and while this is not a solution, but it will minimize the number of errors that we're getting.

We'll have to figure out a proper way to support this functionality eventually though.

Alright so, this is weird. I don't know if this is considered a breaking change or not, but I don't think it is.

Moving the HostAgent's lastSeenOn inside the properties key is technically adding a new field that didn't exist before.
But also, the schema was mentioning the lastSeenOn inside the required properties list...

To be able to tell if it's a breaking change or not, we'd have to understand how existing consumers of the HostAgent schema handle a required property that isn't actually defined in the schema's properties.

const Ajv = require('ajv');

const ajv = new Ajv({
  // extendRefs: true 
});

ajv.addSchema({
  "title": "test",
  "type": "object",
  "properties": {
    "abc": {
      "type": "string"
    }
  },
  "required": ["test"]
}
, 'a.json');

console.log(ajv.validate('a.json', {}));

console.log(ajv.validate('a.json', { test: 1 }));

console.log(ajv.validate('a.json', { test: true }));

console.log(ajv.validate('a.json', { test: 'string' }));

false
true
true
true

Looks like AJV considers this as requiring the property to be present but no restriction on the type.