The default behavior is AND, you can have an OR bracket:
numericFilters: "contributor_ids=42, contributor_ids=12"
The values ββcontributor_ids = 42 and contributor_ids = 12 are only relevant if you have an entry containing both values
numericFilters: "(contributor_ids=42, contributor_ids=12)"
Means contributor_ids = 42 OR contributor_ids = 12
numericFilters: "contributor_ids=10,(contributor_ids=42, contributor_ids=12)"
Means contributor_ids = 10 AND (contributor_ids = 42 OR contributor_ids = 12)
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