ot::Lowpan::MeshHeader::GetHeaderLength() const method

The length of the Mesh Header (in bytes) when written to a frame.

The returned value from this method gives the header length (number of bytes) when the header is written to a frame or message. This should not be used to determine the parsed length (number of bytes read) when the Mesh Header is parsed from a frame/message (using `ParseFrom()` methods).