fix: allow excess protocol-specific fields on Binding (issue #735)

.changeset/735-binding-excess.md

@@ -0,0 +1,5 @@
+---
+'@asyncapi/parser': patch
+---
+
+Allow protocol-specific excess properties on the `Binding` type (issue #735).

packages/parser/src/spec-types/v2.ts

@@ -440,6 +440,8 @@ export interface CorrelationIDObject extends SpecificationExtensions {
 
 export interface Binding {
   bindingVersion?: string;
+  // protocol-specific binding fields (excess properties)
+  [propName: string]: any;
 }
 
 export interface SpecificationExtensions {

packages/parser/src/spec-types/v3.ts

@@ -484,6 +484,8 @@ export interface AsyncAPISchemaDefinition extends SpecificationExtensions {
 
 export interface Binding {
   bindingVersion?: string;
+  // protocol-specific binding fields (excess properties)
+  [propName: string]: any;
 }
 
 export interface SpecificationExtensions {

packages/parser/test/models/v2/bindings.spec.ts

@@ -61,4 +61,13 @@ describe('Bindings model', function () {
       expect(bindings.extensions().get('x-anotherOne')?.value()).toEqual({ someKey: 123 });
     });
   });
+
+  describe('excess properties (issue #735)', function () {
+    it('should preserve protocol-specific excess fields on a binding value', function () {
+      const b = new Binding({ clientId: 'my-client', clean: true } as any, { asyncapi: {} as any, pointer: '', protocol: 'mqtt' });
+      const value = b.value() as Record<string, any>;
+      expect(value).toHaveProperty('clientId', 'my-client');
+      expect(value).toHaveProperty('clean', true);
+    });
+  });
 });