Remove unnecessary generic type arguments

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=175155365

java/google/registry/model/eppinput/EppInput.java

@@ -131,7 +131,7 @@ public class EppInput extends ImmutableObject {
     ResourceCommand resourceCommand = getResourceCommand();
     return resourceCommand instanceof SingleResourceCommand
         ? Optional.of(((SingleResourceCommand) resourceCommand).getTargetId())
-        : Optional.<String>empty();
+        : Optional.empty();
   }
 
   /**