Enable AvoidStarImport Checkstyle check (#5420)

core/src/main/java/hudson/Util.java

@@ -43,7 +43,19 @@ import org.apache.tools.ant.types.FileSet;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
 
-import java.io.*;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.Closeable;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.PrintStream;
+import java.io.Reader;
+import java.io.StringReader;
+import java.io.Writer;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.net.InetAddress;
@@ -76,7 +88,20 @@ import java.text.ParseException;
 import java.time.LocalDate;
 import java.time.ZoneId;
 import java.time.temporal.ChronoUnit;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Date;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.MissingResourceException;
+import java.util.Properties;
+import java.util.ResourceBundle;
+import java.util.Set;
+import java.util.SimpleTimeZone;
+import java.util.StringTokenizer;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Supplier;