Why do we need the additional single quotes?

Hello, since ROS 2 doesn't support setting parameters as a list of lists, Boost Property Tree library has been used.
invalid_regions is assumed as a string and parsed with the library. To make it string, I have added another set of quotes.

Let's use this instead, boost is too heavy for this task.

<depend>nlohmann-json-dev</depend> can be added to the package.xml file and all should work fine.

And the rest of the code will be much cleaner and also will be error checked:

// Assuming `nlohmann::json` namespace is available as `json`
void parseInvalidRegions(const std::string& regions_json) {
    // Parse the JSON string
    auto invalid_regions_json = json::parse(regions_json);

    // Clear existing regions
    sensor_configuration_.invalid_regions.clear();

    // Iterate over the parsed JSON array
    for (const auto& region : invalid_regions_json) {
        // Extract the ring number, start angle, and end angle from each sub-array
        int ring_number = region[0];
        uint16_t start = region[1];
        uint16_t end = region[2];

        // Add the InvalidRegion to the map under the corresponding ring number
        sensor_configuration_.invalid_regions[ring_number].emplace_back(InvalidRegion{start, end});
    }
}

This check has to be calculated with a search in the excluded regions parameters for every point, which is causing the performance overhead. We suggest pre-computing the binary value for each azimuth and channel value to make a map, allowing a single conditional to check if the point is valid or not.

In my opinion, it would be more user-friendly to have a float here (34.44) and for Nebula to convert it to an int 3444 internally.

As the filter is not inherently a feature of the sensor, please move it to a class RingSectionFilter in its own header file.

As it is now, the bool and std::map could be assigned in invalid ways, e.g. ring_section_filter = false; excluded_ring_sectors = { /* not empty */ };. We should avoid such possibilities as much as possibe to make Nebula safer and more maintainable.
This would be cleaner as std::optional<RingSectionFilter>.

since the filter is not an inherent feature of the sensor, please move this to a class RingSectionFilter (and as @drwnz mentioned, precompute in the class's constructor).

To make clear to the reader that the existing FOV filtering (min_angle and max_angle) and the new RingBasedFilter are separate features, please refactor to:

To make clear to the reader that the existing FOV filtering (min_angle and max_angle) and the new RingBasedFilter are separate features, please refactor to:

To make clear to the reader that the existing FOV filtering (min_angle and max_angle) and the new RingBasedFilter are separate features, please refactor to:

As noted in README.md, I think specifying floats (35.00, 69.00 etc.) is more easily understandable to the user.

Also, please set the default to an emty filter. Instead, a `description=". Example: '[0, 3500, 6900], ...'" would be nice.

As noted in velodyne_common.hpp, it would be nicer (better separation of concerns) if the configuration contained a std::optional<RingBasedFilter> instead of bool ring_section_filter and excluded_ring_sectors.

"It's" sounds a bit informal, how about: