Check lower bound of replicant values for rules

server/src/main/java/io/druid/server/coordinator/rules/ForeverLoadRule.java

@@ -36,6 +36,7 @@ public class ForeverLoadRule extends LoadRule
       @JsonProperty("tieredReplicants") Map<String, Integer> tieredReplicants
   )
   {
+    validateTieredReplicants(tieredReplicants);
     this.tieredReplicants = tieredReplicants;
   }
 

server/src/main/java/io/druid/server/coordinator/rules/IntervalLoadRule.java

@@ -41,6 +41,7 @@ public class IntervalLoadRule extends LoadRule
       @JsonProperty("tieredReplicants") Map<String, Integer> tieredReplicants
   )
   {
+    validateTieredReplicants(tieredReplicants);
     this.interval = interval;
     this.tieredReplicants = tieredReplicants;
   }

server/src/main/java/io/druid/server/coordinator/rules/LoadRule.java

@@ -20,6 +20,7 @@ package io.druid.server.coordinator.rules;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.MinMaxPriorityQueue;
+import com.metamx.common.IAE;
 import com.metamx.emitter.EmittingLogger;
 import io.druid.server.coordinator.BalancerStrategy;
 import io.druid.server.coordinator.CoordinatorStats;
@@ -240,6 +241,13 @@ public abstract class LoadRule implements Rule
     return stats;
   }
 
+  protected void validateTieredReplicants(Map<String, Integer> tieredReplicants){
+    for (Map.Entry<String, Integer> entry: tieredReplicants.entrySet()) {
+      if (entry.getValue() < 0)
+        throw new IAE("Replicant value [%d] is less than 0, which is not allowed", entry.getValue());
+    }
+  }
+
   public abstract Map<String, Integer> getTieredReplicants();
 
   public abstract int getNumReplicants(String tier);

server/src/main/java/io/druid/server/coordinator/rules/PeriodLoadRule.java

@@ -42,6 +42,7 @@ public class PeriodLoadRule extends LoadRule
       @JsonProperty("tieredReplicants") Map<String, Integer> tieredReplicants
   )
   {
+    validateTieredReplicants(tieredReplicants);
     this.period = period;
     this.tieredReplicants = tieredReplicants;
   }