I'm using custom_filters_score to boost documents that match one or
more filters. Documents matching more of those filters should receive
a larger boost, but only up to a point.
For example a document matching 1 filters might get a boost of 1.2,
one matching 2 filters a boost of 1.44 but a document matching 3
filters would be capped at 1.44 (rather than 1.2 *1.44).
I can't find anything that looks like it might do that but I'd love to
be proved wrong. Failing that would a custom_filters_score option
along the lines of max_boost be of interest ? If so pointers to where
to start digging in the source gratefully accepted!