Fix two warnings thrown by Eclipse

One is an unnecessary import and the other is an incorrectly named
Javadoc parameter.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=153095269

java/google/registry/util/ComparingInvocationHandler.java

@@ -131,7 +131,7 @@ public abstract class ComparingInvocationHandler<T> implements InvocationHandler
    * stack trace for example), override this method with the desired implementation.
    *
    * @param method the method whose return value is given
-   * @param exception the exception thrown by a call to method
+   * @param throwable the exception thrown by a call to method
    */
   protected String stringifyThrown(
       @SuppressWarnings("unused") Method method,