Eclipse Californium (Cf) CoAP Framework 2.7.0

This minor release fixes the missing endpoint context check for blockwise follow-up requests.

block1 request will be conisdered as 4.08/REQUEST_ENTITY_INCOMPLETE, block2 request will be forwarded to the application layer in order to decide there.

It extends the API and therefore requires a minor version.

It compiles with using the old APIs as well, but that doesn't provide the added protection.

If the CoapStackFactory or the CoapUdpStack is used for custom extension, please adapt your custom code in order to get the protection.