noop filter needed when I want to merge jsonSchema annotation, not replace

[ryskajakub]

What version of Effect is running?

"@effect/platform": "^0.69.24"

What steps can reproduce the bug?

add a schema to a handler in http platform

  const s1 = Schema.Union(Schema.Struct({ _tag: Schema.Literal('s1') }), Schema.Struct({ _tag: Schema.Literal('s2') }));

  const s1Annotated = s1.annotations({
    jsonSchema: {
      discriminator: {
        propertyName: '_tag',
      },
    },
  });

use in a api:

HttpApiGroup.make('resource')
  .add(
    HttpApiEndpoint.put('myResource', '/res')
      .setPayload(s1Annotated)

generate swagger docs:

const HttpLive = HttpApiBuilder.serve(errorLogger).pipe(
  Layer.provide(HttpApiSwagger.layer()),

then extract the openapi definition from the generated docs and inspect it

What is the expected behavior?

add the discriminator clause to the part describing the data structure like this

          anyOf:
            - $ref: '#/components/schemas/S1'
            - $ref: '#/components/schemas/S2'
          discriminator:
            propertyName: _tag

What do you see instead?

only the discriminator clause, without the anyOf clause

          discriminator:
            propertyName: _tag

Additional information

this can actually be fixed by adding noop filter to the data structure and attaching the jsonSchema to it.

  return union.pipe(Schema.filter((x) => true)).annotations({
    jsonSchema: {
      discriminator: {
        propertyName: '_tag',
        mapping,
      },
    },
  });

this is because the jsonSchema annotation is handled differently for the refinements
https://github.com/Effect-TS/effect/blame/c8d20b0827a30e95a0fe192113e82b72c8bfb5cd/packages/platform/src/OpenApiJsonSchema.ts#L350