all function
Creates a composite filter which groups one or more field filters with the ALL
operator.
All the field filters should pass in order for the composite filter to pass.
Implementation
Composite all(Iterable<SimpleFilter> filters) {
return Composite._(CompositeFilter()
..operator = CompositeFilter_CompositeOperator.ALL
..filter.addAll(filters.map((f) => f.filter))
..freeze());
}