OSGi's APIs were designed against the Java 1.1 platform, and as such use older classes like Dictionary and lack some of the newer Java language features like Generics. Although this has allowed OSGi to run on anything from a high-end supercomputer to a low-end mobile phone, the sweet spot of application development (combined with Java 1.4's End-of-Life) process) is now focussed on Java 1.5, 1.6 or 1.7 (or whatever marketing monikers they happen to be known by).
To that end, there has been experimental investigation to provide a newer version of the OSGi libraries that will support generics. This has been possible with the advent of a compatibility layer (referred to as thunking) which performs on-the-fly translation between the Java 5 variant and the traditional one.
Peter Kriens and BJ Hargrave gave the TS-4966 talk at JavaOne 2009 with lessons learned from this prototype, including how OSGi can take advantage of the JSR 294 language features due to come out for 1.7. Although this is still at the investigation phase, it will further bolster the widespread adoption of OSGi.