static public void validateThatReadyCopiesIsCompatibleWithRedundancy(int totalRedundancy, int totalReadyCopies, int groupCount) {
        if (totalRedundancy % groupCount != 0) {
            throw new IllegalArgumentException("Expected equal redundancy per group");
        }
        if (totalReadyCopies % groupCount != 0) {
            throw new IllegalArgumentException("Expected equal amount of ready copies per group, but " +
                                               totalReadyCopies + " ready copies is specified with " + groupCount + " groups");
        }
        if (totalReadyCopies == 0) {
            throw new IllegalArgumentException("No ready copies configured. At least 1 is required.");
        }
    }
Class used to validate that hierarchic distribution is correctly setup when having an indexed content cluster.

Note that this class does not implement the com.yahoo.vespa.model.application.validation.Validator interface,
but is instead used in the context of com.yahoo.vespa.model.ConfigProducer.validate() such that it can be unit tested
without having to build the complete vespa model.

@author geirst
config-model/src/main/java/com/yahoo/vespa/model/content/IndexedHierarchicDistributionValidator.java