Incompatibile SockJS! Main site uses: "1.1.4", the iframe: "1.0.0". How to deal with that?

I fixed it by manually hardcoding the SockJS version on the server-side (Spring/Java) by

@Override
public void registerStompEndpoints( StompEndpointRegistry registry ) 
{
     registry.addEndpoint( "/socket" )
        .setAllowedOrigins( "*" )
        .withSockJS( )
        .setClientLibraryUrl( "https://cdn.jsdelivr.net/sockjs/1.1.4/sockjs.min.js" ); 
}

Update: To load the JS library (local) using a relative path

@Override
public void registerStompEndpoints( StompEndpointRegistry registry )
{
   registry.addEndpoint( "/socket" )
       .setAllowedOrigins( "*" )
       .withSockJS( )
       .setClientLibraryUrl( "../lib/sockjs-client/dist/sockjs.min.js" ); // Added
}