The flow expression parser needs to fully support the documented supported expression types

```
Section 24.5 "Writing Java expressions as annotation arguments" lists the 
subset of legal Java expressions supported as arguments to annotations. The 
flow expression parser does not currently fully support all of these. Ensure 
that it does, or modify the documentation accordingly.
```

Original issue reported on code.google.com by `jtha...@cs.washington.edu` on 19 Mar 2015 at 4:24
