@discriminates opaqueType clashing with named type

[darylgraham]

Alternate issue title: @Discriminates needs a hierarchy traversal restriction

I was using the standard schema from @frontside/backstage-plugin-graphql-backend-module-catalog and came across an interesting condition.

For reference, here is a snippet of the shipped schema file:

extend interface Entity @discriminates(with: "kind", opaqueType: "OpaqueEntity") {
  name: String! @field(at: "metadata.name")
  kind: String! @field(at: "kind")
  ...
}

interface Component
  @implements(interface: "Entity")
  @discriminates(with: "spec.type", opaqueType: "OpaqueComponent")
  @discriminationAlias(value: "service", type: "Service")
  @discriminationAlias(value: "website", type: "Website")
  @discriminationAlias(value: "library", type: "Library") {
  type: String! @field(at: "spec.type")
  ...
}

interface Resource
  @implements(interface: "Entity")
  @discriminates(with: "spec.type", opaqueType: "OpaqueResource")
  @discriminationAlias(value: "database", type: "Database") {
  type: String! @field(at: "spec.type")
  ...
}

Component and Resource are both entities that extend the Entity interface, and they both have a field spec.type which is used to drill down to more specific entity types via @discriminates.

In my catalog I have a Resource that is described with spec.type: service, which causes an error to occur when querying the graphql endpoint:

Query:

{
  entities(first: 10, filter: { match: { kind:"Resource"} }) {
    edges {
      node {
        kind
        name
        namespace
      }
    }
  }
}

Error message in the GraphiQL client:

{
  "errors": [
    {
      "message": "Unexpected error.",
      "locations": [
        {
          "line": 4,
          "column": 7
        }
      ],
      "path": [
        "entities",
        "edges",
        1,
        "node"
      ],
      "extensions": {
        "originalError": {
          "message": "Can't resolve type for node with \"Node@Catalog@{\"ref\":\"resource:digital/live-feeder-db\"}\" id. The \"Service\" type which was discriminated by Resource interface does not implement the \"Resource\" interface",
          "stack": "Error: Can't resolve type for node with \"Node@Catalog@{\"ref\":\"resource:digital/live-feeder-db\"}\" id. The \"Service\" type which was discriminated by Resource interface does not implement the \"Resource\" interface\n    at GraphQLInterfaceType.resolveType (/workspaces/backstage/backstage/node_modules/@frontside/hydraphql/src/mapInterfaceType.ts:242:19)\n    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)\n    at async /workspaces/backstage/backstage/node_modules/@graphql-tools/executor/cjs/execution/promiseForObject.js:18:35\n    at async Promise.all (index 0)"
        }
      }
    }
  ],
  "data": {
    "entities": null
  }
}

In the backend logs:

2024-10-27T23:58:42.545Z graphql error Can't resolve type for node with "Node@Catalog@{"ref":"resource:digital/live-feeder-db"}" id. The "Service" type which was discriminated by Resource interface does not implement the "Resource" interface

GraphQL request:4:7
3 |     edges {
4 |       node {
  |       ^
5 |         kind 

I can resolve the error by updating the schema to this:

interface Component
  @implements(interface: "Entity")
  @discriminates(with: "spec.type", opaqueType: "OpaqueComponent")
  @discriminationAlias(value: "service", type: "ServiceComponent")
  @discriminationAlias(value: "website", type: "WebsiteComponent")
  @discriminationAlias(value: "library", type: "LibraryComponent") {
  type: String! @field(at: "spec.type")
  ...
}

interface Resource
  @implements(interface: "Entity")
  @discriminates(with: "spec.type", opaqueType: "OpaqueResource")
  @discriminationAlias(value: "service", type: "ServiceResource")
  @discriminationAlias(value: "database", type: "DatabaseResource") {
  type: String! @field(at: "spec.type")
  ...
}

It looks like the request is matching the @discriminate function on Entity to map the entity to a Resource, but then when Resource discriminates the spec.type field, it is reading the definition from Component for type Service instead of using opaqueType.