src/java.base/share/classes/sun/nio/cs/AbstractCharsetProvider.java

*** 109,118 ****
--- 109,124 ----
              remove(aliasNameMap, name);
              cache.clear();
          }
      }
  
+     protected boolean hasCharset(String name) {
+         synchronized (this) {
+             return classMap.containsKey(name);
+         }
+     }
+ 
      /* Late initialization hook, needed by some providers
       */
      protected void init() { }
  
      private String canonicalize(String charsetName) {