Overview of changes:

• The overriding of a single codec takes place in CodecRegistry.register() : if the exact same CQL-Java mapping already exists, the existing codec is replaced by the new one (note the additional log warning).
• The on the fly overriding of collection codecs is more complex: there is now a new CodecFactory class that can be subclassed for this purpose.
• Behavior in case of overlapping codecs didn't change: it is still possible to register more than one codec for the same CQL type.

Note: the CodecFactory class allow users to override the on-the-fly instantiation mechanism, but we could live without it. If the user knows which exact list types he needs to handle, the following code:

CodecFactory factory = new DefaultCodecFactory() {
    protected <T> TypeCodec<List<T>> newListCodec(TypeCodec<T> eltCodec) {
        return new MyListCodec<T>(eltCodec);
    }
};
CodecRegistry registry = new CodecRegistry(factory);

Could easily be replaced with:

CodecRegistry registry = new CodecRegistry();
registry.register(new MyListCodec(IntCodec.instance));
registry.register(new MyListCodec(VarcharCodec.instance));
// etc. register all list types required by the application