addressing review comments

Author: yue9944882

util/src/main/java/io/kubernetes/client/util/ModelMapper.java

@@ -21,7 +21,12 @@
 import io.kubernetes.client.openapi.ApiException;
 import java.io.IOException;
 import java.time.Duration;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 import org.apache.commons.lang3.tuple.MutablePair;
 import org.apache.commons.lang3.tuple.Pair;
 import org.slf4j.Logger;

util/src/test/java/io/kubernetes/client/util/ModelMapperTest.java

@@ -91,7 +91,6 @@ public void test() throws IOException, ApiException {
     // TODO(yue9944882): move this to an integration test
     Discovery discovery = new Discovery(ClientBuilder.defaultClient());
     ModelMapper.refresh(discovery);
-    ModelMapper.refresh(discovery);
 
     assertEquals(
         new GroupVersionKind("", "v1", "Pod"), ModelMapper.getGroupVersionKindByClass(V1Pod.class));