[PATCH] Avoid redundant HashMap.containsKey call in java.util.regex{Matcher, Pattern}

Pattern.namedGroupsMap and Matcher.namedGroups contains only non-null values.
It means instead of separate containsKey+get calls, we can use single HashMap.get call and then compare result with null.
Result code is a bit simpler and faster.

Author: turbanoff

src/java.base/share/classes/java/util/regex/Matcher.java

@@ -1819,9 +1819,10 @@ char charAt(int i) {
     int getMatchedGroupIndex(String name) {
         Objects.requireNonNull(name, "Group name");
         checkMatch();
-        if (!namedGroups().containsKey(name))
+        Integer index = namedGroups().get(name);
+        if (index == null)
             throw new IllegalArgumentException("No group with name <" + name + ">");
-        return namedGroups().get(name);
+        return index;
     }
 
     private void checkGroup(int group) {

src/java.base/share/classes/java/util/regex/Pattern.java

@@ -2612,14 +2612,15 @@ private int escape(boolean inclass, boolean create, boolean isrange) {
             if (read() != '<')
                 throw error("\\k is not followed by '<' for named capturing group");
             String name = groupname(read());
-            if (!namedGroupsMap().containsKey(name))
+            Integer index = namedGroupsMap().get(name);
+            if (index == null)
                 throw error("named capturing group <" + name + "> does not exist");
             if (create) {
                 hasGroupRef = true;
                 if (has(CASE_INSENSITIVE))
-                    root = new CIBackRef(namedGroupsMap().get(name), has(UNICODE_CASE));
+                    root = new CIBackRef(index, has(UNICODE_CASE));
                 else
-                    root = new BackRef(namedGroupsMap().get(name));
+                    root = new BackRef(index);
             }
             return -1;
         case 'l':