src/java.base/share/classes/java/time/Period.java

@@ -81,12 +81,10 @@
 import java.time.temporal.TemporalAccessor;
 import java.time.temporal.TemporalAmount;
 import java.time.temporal.TemporalQueries;
 import java.time.temporal.TemporalUnit;
 import java.time.temporal.UnsupportedTemporalTypeException;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 

@@ -150,12 +148,11 @@
             Pattern.compile("([-+]?)P(?:([-+]?[0-9]+)Y)?(?:([-+]?[0-9]+)M)?(?:([-+]?[0-9]+)W)?(?:([-+]?[0-9]+)D)?", Pattern.CASE_INSENSITIVE);
 
     /**
      * The set of supported units.
      */
-    private static final List<TemporalUnit> SUPPORTED_UNITS =
-            Collections.unmodifiableList(Arrays.<TemporalUnit>asList(YEARS, MONTHS, DAYS));
+    private static final List<TemporalUnit> SUPPORTED_UNITS = List.of(YEARS, MONTHS, DAYS);
 
     /**
      * The number of years.
      */
     private final int years;