add test reproducing the error

packages/parser/test/mocks/UserRegistered.yml

@@ -0,0 +1,16 @@
+components:
+  schemas:
+    UserRegisteredType:
+      type: string
+      enum: [ UserRegistered ]
+    UserRegistered:
+      type: object
+      additionalProperties: false
+      required:
+        - type
+        - name
+      properties:
+        type:
+          $ref: "#/components/schemas/UserRegisteredType"
+        name:
+          type: string

packages/parser/test/mocks/simple-with-external-refs.yaml

@@ -0,0 +1,42 @@
+asyncapi: '3.0.0'
+info:
+  title: User API
+  version: '1.0.0'
+
+servers:
+  local:
+    host: localhost:3000
+    protocol: ws
+
+channels:
+  onUserRegistered:
+    messages:
+      UserRegistered:
+        name: UserRegistered
+        title: UserRegistered
+        payload:
+          $ref: 'UserRegistered.yml#/components/schemas/UserRegistered'
+  onUserLogged:
+    messages:
+      UserLogged:
+        name: UserLogged
+        title: UserLogged
+        payload:
+          $ref: '#/components/schemas/UserLogged'
+
+components:
+  schemas:
+    UserLoggedType:
+      type: string
+      enum: [UserLogged]
+    UserLogged:
+      type: object
+      additionalProperties: false
+      required:
+        - type
+        - name
+      properties:
+        type:
+          $ref: '#/components/schemas/UserLoggedType'
+        name:
+          type: string

packages/parser/test/parser.spec.ts

@@ -1,6 +1,9 @@
+import path from 'path';
+import fs from 'fs';
 import { Spectral } from '@stoplight/spectral-core';
 import { Parser } from '../src/parser';
 import { AsyncAPISchemaParser } from '../src/schema-parser/asyncapi-schema-parser';
+import { AsyncAPIDocumentInterface } from "../src";
 
 describe('Parser class', function() {
   it('should create Parser instance', async function() {
@@ -18,4 +21,20 @@ describe('Parser class', function() {
     parser.registerSchemaParser(AsyncAPISchemaParser());
     expect((parser as any).parserRegistry.size).toBeGreaterThan(1);
   });
+
+  it('should give correct names to external references', async function() {
+    const parser = new Parser();
+    const source = path.resolve(__dirname, './mocks/simple-with-external-refs.yaml');
+    const nestedSchemas = fs.readFileSync(source, 'utf8');
+
+    const { document } = await parser.parse(nestedSchemas, { source });
+
+    const channels = (document as AsyncAPIDocumentInterface).channels().all();
+    const onUserRegisteredChannel = channels[0]
+    const onUserLoggedChannel = channels[1]
+    const userRegisteredMessagePayload = onUserRegisteredChannel.messages().all()[0].payload()?.json() as any;
+    const userLoggedMessagePayload = onUserLoggedChannel.messages().all()[0].payload()?.json() as any;
+    expect(userRegisteredMessagePayload?.["x-parser-schema-id"]).toBe("UserRegistered");
+    expect(userLoggedMessagePayload?.["x-parser-schema-id"]).toBe("UserLogged");
+  });
 });