Encoding maps in CBOR in canonical form (finite length)

[philips77]

This PR changes the way how maps are encoded to CBOR by using a finite length.

Before

Maps were encoded with BF token (indefinite length map), followed by key-value pairs and FF stop sign.

Example

BF...FF - a map oa any size

After

The new CanonicalMapSerializer uses writeStartObject(Object, Int) to encode the map using its length instead.

Example

A0 - empty map
A3... - map with 3 key-value pairs
AF... - map with 15 pairs
B0... - map with 16 pairs
B7... - map with 23 pairs
B8-18... map with 24 pairs

Note

Canonical form of encoding maps is currently not supported in Jackson library nor in Kotlin CBOR. The proper implementation should rather add a Feature to the CBORFactory or somewhere. This one is using a bit of a hack.

This PR is related to FasterXML/jackson-dataformats-binary#3