Allow fields to be json literals

[GoogleCodeExporter]

In the jclouds project, we often encounter semi-structured data.  For example, 
the structure is known to a certain depth, and after which we'd like to defer 
parsing to an extension.

For example, a json schema could be known to have attributes, which are not 
typed.  We'd like to defer parsing of these attributes.

For example, I'd like to parse the following:

{
    "name": "elmo",
    "attributes": {
        "custom/1": {
            "favorite": "berries"
        },
        "custom/2": 1000
    }
}

into a class like this:

class Thing {
    String name;
    Map<String, String> attributes; 
}

Original issue reported on code.google.com by adrian.f...@gmail.com on 15 May 2011 at 12:28