content-assist for annotation attributes doesn't work when spaces are involved

Content-assist for Spring annotation attributes fail when there is a space involved, e.g.

```
@Resource(name = <*>)
```

does not show content-assist for `@Resource`, whereas

```
@Resource(name =<*>)
```

does show the correct content-assist proposals. This is a general problem of the content-assist for annotation attributes, not just for the `@Resource` annotation.