Remove trailing whitespace in files

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135386752

java/google/registry/model/domain/GracePeriod.java

@@ -116,7 +116,7 @@ public class GracePeriod extends ImmutableObject {
     return instance;
   }
 
-  /** 
+  /**
    * Creates a GracePeriod for an (optional) OneTime billing event.
    *
    * <p>Normal callers should always use {@link #forBillingEvent} instead, assuming they do not