Remove unnecessary explicit generic type declarations

They can be inferred correctly even in Java 7, and display as
compiler warnings in IntelliJ.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=173451087

java/google/registry/batch/DeleteContactsAndHostsAction.java

@@ -200,7 +200,7 @@ public class DeleteContactsAndHostsAction implements Runnable {
               new DeleteEppResourceReducer(),
               ImmutableList.of(
                   // Add an extra shard that maps over a null domain. See the mapper code for why.
-                  new NullInput<DomainBase>(),
+                  new NullInput<>(),
                   EppResourceInputs.createEntityInput(DomainBase.class)))));
     } catch (Throwable t) {
       logger.severefmt(t, "Error while kicking off mapreduce to delete contacts/hosts");