The following file has an incorrect header format:

src/hotspot/share/gc/g1/g1FullGCCompactionPoint.cpp
src/hotspot/share/gc/g1/g1FullGCCompactTask.cpp
src/hotspot/share/gc/g1/g1FullGCMarker.inline.hpp

The header below was integrated by JDK-8199735
 * Copyright (c) 2017, 2018 Oracle and/or its affiliates. All rights reserved.

Missing comma after year, YEAR should be "2018,"
%YEARS% should be one of two formats

    "YEAR,"
    "YEAR, YEAR,"

You can verify the header is correct with make/scripts/lic_check.sh (from JDK 10 WS) to make sure each file now passes.
The template is located at:
  make/templates/gpl-header
  make/templates/gpl-cp-header