private String getFilterValue(List<FilterClause> singletonFilters) { if (singletonFilters == null) { return NO_FIELD; } // Otherwise, it's a list of size 1 with a singular value, which has been already validated FilterClause filter = singletonFilters.get(0); Object value = filter.getValues().get(0); if (filter.hasNull(value)) { return NO_FIELD; } return makeKeyEntry(filter.getValue(value)); }