Number of incoming records by input plugin

Is it possible to have metric showing number of records by input plugin?

Seems it's only possible to have custom filter counting eg. by tag:
```

@type prometheus

name fluentd_input_status_num_records_total
type counter
desc The total number of incoming records

tag ${tag}
hostname ${hostname}



```

I would like the same thing but per input plugin.

One solution might be to let input plugins append field with plugin name into processed record. But that would require patching input plugins, can't find any native way yet.