Here is my call:

```
this.enumService.getData('ContentStatus'),

```

It's giving an error as my definition is:

```
getData(controller: any, params: any);

```

The function looks like this:

```
getData = (controller, params) => {
    if (!params) { params = "" }
    var defer = this.$q.defer();

```

How can I fix the definition and the function so a null is allowed?