fix javadoc errors

Author: stoty

core/src/main/java/org/apache/calcite/avatica/util/SecurityUtils.java

@@ -222,10 +222,7 @@ public static <T> T callAs(Subject subject, Callable<T> action) {
    * <p>
    * Gets the current subject
    * </p>
-   * @param subject the subject this action runs as
-   * @param action the action to run
-   * @return the result of the action
-   * @param <T> the type of the result
+   * @return the current subject
    */
   @SuppressWarnings("unchecked")
   public static Subject currentSubject() {