Breeze Loading metadata or entity type on demand

Question

To reduce the size of breeze meta data, we are planning to make entity based meta data. So that each entity meta data will be downloaded from the server on demand.

Previously, the metadata was downloaded by breeze(normal behavior) and it works fine for us. To achieve the on demand loading of meta data, i tried the "importMetadata" functionality. But "entityManager.HasChanges()" always return "false", but the user input data is there in the json entity.

I used the below code snippet to do the same.

   constructor(private bwhttp: BWHttp) {
    this.em = new EntityManager(this.serviceName);
    this.em.dataService.hasServerMetadata = false;
    this.em.saveOptions = new SaveOptions({ allowConcurrentSaves: true });        
}

public getData(data: string, formType?, args?, system?, taxtype?) {

    this.bwhttp.get("http://someserver.cdn.com/metadata/"+formType+".json").subscribe(httpdata => {
        var metadata = JSON.stringify(httpdata['_body']);
        this.em.metadataStore.importMetadata(metadata, true);
        this.getDataInternal(data, formType, args, system, taxtype);
    });

}
public saveChanges(propertyName: string) {
    this.applyPropertyChanges(propertyName);
    if (!this.em.hasChanges()) return;//it always gives false.
    this.em
        .saveChanges()
        .then(result => {
            this.status = "Changes Saved."
            this.hassaved.next(true);
        })
        .catch(err => {
            this.status = "Error:" + err.toString();
            this.em.rejectChanges();
        });
 }

Did i missed anything on this? Please help me on this.