code: public void setRulesets(SPARQLRuleset ... rulesets) {
          if(notNull(rulesets)) {
              List<SPARQLRuleset> list = new ArrayList<>();
              for(Object r : rulesets) {
                  if(r != null && rulesets.length > 0) {
                      list.add((SPARQLRuleset)r);
                  }
              }
              this.ruleset = list.toArray(new SPARQLRuleset[list.size()]);
          }else{
              this.ruleset = null;
          }
      }
docs: setter for rulesets, filters out nulls
  
  @param rulesets