https://www.elastic.co/guide/en/elasticsearch/reference/master/search-aggregations-bucket-significantterms-aggregation.html#_parameters_5

Presumably one can select between jlh, mutual_information, chi_square, gnd, percentage or script_heuristic.

No usage example is provided for jlh, but it is mentioned later:

https://www.elastic.co/guide/en/elasticsearch/reference/master/search-aggregations-bucket-significantterms-aggregation.html#_which_one_is_best

There should be an example for jlh, even if it has no params.