DDSXTY14 — XCDR2 serialization of non-trivial maps

This issue was raised by Idar Carlsen (Kongsberg Defence & Aerospace)

In the X-Types 1.3 specification, under the “7.4.3.5.3 Complete Serialization Rules” section, it says that non-trivial maps should have a DHEADER when XCDR2 is used (rule 15). Notably, it only has the DHEADER – unlike the version 1 encoding, the size (in terms of numbers of entries) of the map is not serialized. This differs from how sequences are serialized, as they include the size as well. Is this correct, or should the size of the map also be serialized in addition to the DHEADER?

It seems to me that some of the other DDS implementations include the size, even though the specification does not say so.

Fix serialization of maps

There is an error in the rule for map serialization needs had ommited serializing the number of elements which inconsistent with their treatment 'as a sequence of map entries'. It also does not match what vendors are actually doing.
The rule should be updated to also serialize the number elements.