Merge pull request #2791 from ebean-orm/feature/InternString

Just use String.intern() now that we are on min Java 11 runtime.

ebean-core/src/main/java/io/ebeaninternal/server/core/InternString.java

@@ -1,38 +1,14 @@
 package io.ebeaninternal.server.core;
 
-import java.util.HashMap;
-import java.util.concurrent.locks.ReentrantLock;
-
 /**
  * Used to reduce memory consumption of strings used in deployment processing.
- * <p>
- * Using this for now instead of String.intern() to avoid any unexpected
- * increase in PermGen space.
  */
 public final class InternString {
 
-  private static final HashMap<String, String> map = new HashMap<>();
-
-  private static final ReentrantLock lock = new ReentrantLock();
-
   /**
    * Return the shared instance of this string.
    */
   public static String intern(String s) {
-    if (s == null) {
-      return null;
-    }
-    lock.lock();
-    try {
-      String v = map.get(s);
-      if (v != null) {
-        return v;
-      } else {
-        map.put(s, s);
-        return s;
-      }
-    } finally {
-      lock.unlock();
-    }
+    return s == null ? null : s.intern();
   }
 }