Remove unnecessary generic type arguments

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

javatests/google/registry/xml/XmlTestUtils.java

@@ -261,7 +261,7 @@ public class XmlTestUtils {
         XML.toJSONObject(xml),
         null,
         ImmutableSet.copyOf(ignoredPaths),
-        ImmutableMap.<String, String>of()).getValue();
+        ImmutableMap.of()).getValue();
   }
 }