public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("Source id: ").append(id).append("\n").
                append("Leader provider: ").append(
                leader.getParentProvider().getComponentId()).append("\n").
                append("Participants:");

        for (Source participant : participants) {
            builder.append("\n").append("    Provider: ").append(
                    participant.getParentProvider().getComponentId());
        }
        return builder.toString();
    }
A set of sources with the same name, each associated with a different provider, that fills the same role.

@author Tony Vaagenes
config-model/src/main/java/com/yahoo/vespa/model/container/search/searchchain/SourceGroup.java