math_56.diff

diff --git a/src/main/java/org/apache/commons/math/util/MultidimensionalCounter.java b/src/main/java/org/apache/commons/math/util/MultidimensionalCounter.java
index 56c9ffebc..fd73ad71d 100644
--- a/src/main/java/org/apache/commons/math/util/MultidimensionalCounter.java
+++ b/src/main/java/org/apache/commons/math/util/MultidimensionalCounter.java
@@ -234,6 +234,11 @@ public class MultidimensionalCounter implements Iterable<Integer> {
             indices[i] = idx;
         }
 
+        int correctLastIndex = 0; // defects4j.instrumentation
+        if (Boolean.parseBoolean(System.getProperty("defects4j.instrumentation.enabled"))) { // defects4j.instrumentation
+            correctLastIndex = index - count; // defects4j.instrumentation
+        } // defects4j.instrumentation
+
         int idx = 1;
         while (count < index) {
             count += idx;
@@ -242,6 +247,12 @@ public class MultidimensionalCounter implements Iterable<Integer> {
         --idx;
         indices[last] = idx;
 
+        if (Boolean.parseBoolean(System.getProperty("defects4j.instrumentation.enabled"))) { // defects4j.instrumentation
+            if (indices[last] != correctLastIndex) { // defects4j.instrumentation
+                throw new RuntimeException("[Defects4J_BugReport_Violation]"); // defects4j.instrumentation
+            } // defects4j.instrumentation
+        } // defects4j.instrumentation
+
         return indices;
     }