@Override
      public <T> Codec<T> get(Class<T> clazz, CodecRegistry registry) {
        try {
          return get(clazz);
        } catch (CodecConfigurationException e) {
          return null;
        }
      }
Given existing {@code Gson} instance builds a {@link CodecRegistry}.

@param gson preconfigured instance
@return wrapper for {@code gson}.
mongo/src/org/immutables/mongo/bson4gson/GsonCodecs.java