Refactor Guava functional methods to use lambdas

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=177027488

java/google/registry/reporting/IcannReportingStager.java

@@ -196,7 +196,7 @@ public class IcannReportingStager {
   private String constructTotalRow(List<Integer> totals) {
     StringBuilder rowString = new StringBuilder("Totals,,");
     rowString.append(
-        totals.stream().map((Integer i) -> i.toString()).collect(Collectors.joining(",")));
+        totals.stream().map(Object::toString).collect(Collectors.joining(",")));
     return rowString.toString();
   }