static EndpointGroup of(EndpointGroup... endpointGroups) {
        return of(EndpointSelectionStrategy.weightedRoundRobin(), endpointGroups);
    }
Returns an {@link EndpointGroup} that combines all the {@link Endpoint}s of {@code endpointGroups}.
{@code endpointGroups} can be instances of {@link Endpoint} as well, any {@link EndpointGroup}s and
{@link Endpoint} will all be combined into a single {@link EndpointGroup} that contains the total set.
The {@link EndpointGroup} returned by this method will use
{@link EndpointSelectionStrategy#weightedRoundRobin()} for selecting an {@link Endpoint}.
core/src/main/java/com/linecorp/armeria/client/endpoint/EndpointGroup.java