Fixing compilation

Author: Alexey Kudinkin

hudi-client/hudi-client-common/src/main/java/org/apache/hudi/table/action/commit/BaseMergeHelper.java

@@ -32,7 +32,6 @@
 import org.apache.hadoop.fs.Path;
 
 import java.io.IOException;
-import java.util.Iterator;
 
 /**
  * Helper to read records from previous version of base file and run Merge.