Remove gid_hash_ from AttachmentData (#416)

This member is computed in the constructor which is in turn called
in `rmw_publish`. This hash is not serialized as part of the attachment.

rmw_zenoh_cpp/src/detail/attachment_helpers.cpp

@@ -35,14 +35,12 @@ AttachmentData::AttachmentData(
   const std::array<uint8_t, RMW_GID_STORAGE_SIZE> source_gid)
 : sequence_number_(sequence_number),
   source_timestamp_(source_timestamp),
-  source_gid_(source_gid),
-  gid_hash_(hash_gid(source_gid))
+  source_gid_(source_gid)
 {
 }
 
 AttachmentData::AttachmentData(AttachmentData && data)
 {
-  gid_hash_ = std::move(data.gid_hash_);
   sequence_number_ = std::move(data.sequence_number_);
   source_timestamp_ = std::move(data.source_timestamp_);
   source_gid_ = data.source_gid_;
@@ -66,12 +64,6 @@ std::array<uint8_t, RMW_GID_STORAGE_SIZE> AttachmentData::copy_gid() const
   return source_gid_;
 }
 
-///=============================================================================
-size_t AttachmentData::gid_hash() const
-{
-  return gid_hash_;
-}
-
 zenoh::Bytes AttachmentData::serialize_to_zbytes()
 {
   auto serializer = zenoh::ext::Serializer();
@@ -104,6 +96,5 @@ AttachmentData::AttachmentData(const zenoh::Bytes & bytes)
     throw std::runtime_error("source_gid is not found in the attachment.");
   }
   this->source_gid_ = deserializer.deserialize<std::array<uint8_t, RMW_GID_STORAGE_SIZE>>();
-  gid_hash_ = hash_gid(this->source_gid_);
 }
 }  // namespace rmw_zenoh_cpp

rmw_zenoh_cpp/src/detail/attachment_helpers.hpp

@@ -39,15 +39,13 @@ class AttachmentData final
   int64_t sequence_number() const;
   int64_t source_timestamp() const;
   std::array<uint8_t, RMW_GID_STORAGE_SIZE> copy_gid() const;
-  size_t gid_hash() const;
 
   zenoh::Bytes serialize_to_zbytes();
 
 private:
   int64_t sequence_number_;
   int64_t source_timestamp_;
   std::array<uint8_t, RMW_GID_STORAGE_SIZE> source_gid_;
-  size_t gid_hash_;
 };
 }  // namespace rmw_zenoh_cpp