fix: hello getter

Author: nbbeeken

src/cmap/auth/mongo_credentials.ts

@@ -12,7 +12,7 @@ import type { OIDCRefreshFunction, OIDCRequestFunction } from './mongodb_oidc';
 import { AUTH_MECHS_AUTH_SRC_EXTERNAL, AuthMechanism } from './providers';
 
 // https://github.com/mongodb/specifications/blob/master/source/auth/auth.rst
-function getDefaultAuthMechanism(hello?: Document): AuthMechanism {
+function getDefaultAuthMechanism(hello: Document | null): AuthMechanism {
   if (hello) {
     // If hello contains saslSupportedMechs, use scram-sha-256
     // if it is available, else scram-sha-1
@@ -151,7 +151,7 @@ export class MongoCredentials {
    *
    * @param hello - A hello response from the server
    */
-  resolveAuthMechanism(hello?: Document): MongoCredentials {
+  resolveAuthMechanism(hello: Document | null): MongoCredentials {
     // If the mechanism is not "default", then it does not need to be resolved
     if (this.mechanism.match(/DEFAULT/i)) {
       return new MongoCredentials({

src/cmap/connection.ts

@@ -228,6 +228,10 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
     return this.controller.signal.aborted;
   }
 
+  public get hello() {
+    return this.description.hello;
+  }
+
   // the `connect` method stores the result of the handshake hello on the connection
   public set hello(response: Document | null) {
     this.description.receiveResponse(response);

src/cmap/connection_pool.ts

@@ -621,7 +621,7 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
         )
       );
     }
-    const resolvedCredentials = credentials.resolveAuthMechanism(connection.hello || undefined);
+    const resolvedCredentials = credentials.resolveAuthMechanism(connection.hello);
     const provider = AUTH_PROVIDERS.get(resolvedCredentials.mechanism);
     if (!provider) {
       return callback(