Incorrect copyright header in BCEL 6.4.1 sources

The following file has an incorrect header format:

open/src/java.xml/share/classes/com/sun/org/apache/bcel/internal/Const.java
open/src/java.xml/share/classes/com/sun/org/apache/bcel/internal/ExceptionConst.java
open/src/java.xml/share/classes/com/sun/org/apache/bcel/internal/classfile/ConstantLong.java

   * Copyright (c) 2017, 2020 Oracle and/or its affiliates. All rights reserved.

The second year, YEAR should be "2020,"

You can verify the header is correct with make/scripts/lic_check.sh to make sure each file now passes.

The template is located at:
  make/templates/gpl-header
  make/templates/gpl-cp-header