Power Query: convert table type column to JSON string

Hi,

I have generated a query in PQ with aggregates a column of mail adresses to the unique mails. Now the other columns are put together in one single column of type "table":

When clicking on such a Table link I get

How can i convert that into a JSON string? Ferom my knowledge it should look like:

[
{ "Path": "\\xyz",
"Server": "xyz",
"owner_count": "0"
},
{ "Path": "\\abc",
"Server": "abc",
"owner_count": "2"
}
]

(and so on...)

Any idea how to achieve that? The parse option is greyed out...

Thanks in advance