run command from Java driver for MongoDB

eval command:
{
eval: <function>,
args: [ <arg1>, <arg2> ... ],
nolock: <boolean>
}

Document command = new Document();
command.put("eval", "function () { var result = db.test.findOne( { test_name : \"test_name0\" }); return Object.bsonsize(result); }");
command.put("args", "");
database.runCommand(command);