Header and source files for kernel 4.2.3-15-osmc missing in repos

osmc@ATV:~$ sudo apt-cache search atv-headers
atv-headers-4.2.3-13-osmc - Header files related to Linux kernel, specifically,
osmc@ATV:~$ sudo apt-cache search atv-source
atv-source-4.2.3-13-osmc - Linux kernel source for version 4.2.3-13-osmc

That’s a bug in the new build system. I’m aware of it, and will resolve this in the next release.

For now you can either get the sources manually (from Git) or downgrade to an older kernel. This kernel update only resolves issues with a particular DVB adapter on your device.

thx a lot sam for the quick answer
I can wait until the next release