typo (#890)

diff --git a/modules/core/src/main/java/org/apache/fluo/core/impl/TransactionImpl.java b/modules/core/src/main/java/org/apache/fluo/core/impl/TransactionImpl.java
index 8313220..04d5ef9 100644
--- a/modules/core/src/main/java/org/apache/fluo/core/impl/TransactionImpl.java
+++ b/modules/core/src/main/java/org/apache/fluo/core/impl/TransactionImpl.java
@@ -419,7 +419,7 @@
           numCollisions += cols.size();
         }
 
-        sb.append("Collsions(");
+        sb.append("Collisions(");
         sb.append(numCollisions);
         sb.append("):");