src/main/java/com/conveyal/gtfs/graphql/fetchers/JDBCFetcher.java
static String makeInClause(String filterField, List<String> strings, List<String> parameters) {
        if (strings.size() == 1) {
            return filterEquals(filterField, strings.get(0), parameters);
        } else {
            // Add strings to list of parameters (to be later used to set parameters for prepared statement).
            parameters.addAll(strings);
            String questionMarks = String.join(", ", Collections.nCopies(strings.size(), "?"));
            return String.format("%s in (%s)", filterField, questionMarks);
        }
    }
static String makeInClause(String filterField, List<String> strings, List<String> parameters) {
        if (strings.size() == 1) {
            return filterEquals(filterField, strings.get(0), parameters);
        } else {
            // Add strings to list of parameters (to be later used to set parameters for prepared statement).
            parameters.addAll(strings);
            String questionMarks = String.join(", ", Collections.nCopies(strings.size(), "?"));
            return String.format("%s in (%s)", filterField, questionMarks);
        }
    }
Construct filter clause with '=' (single string) or 'in' (multiple strings) and add values to
list of parameters.