Use standard ASF headers

[paulk-asert]

ASF source files typically have the following first para in the header:

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at:
 * ...

This is close to but not quite the same as the start of the header for most existing source files.

Existing source files typically have a Copyright followed by a year range. The overall year range is now in the NOTICE file and finer grained date information is readily available from git. Also, the "Copyright by original authors" part is implicit, so also not needed in each source file. Trying to maintain the year range in each source file also causes noise/busy work and is sometimes forgotten, so often not accurate. At the start of a new year, ASF projects typically just update their NOTICE file(s) and they are done.

[paulk-asert]

I'll create a PR

[paulk-asert]

There is an issue and PR. I'll close the discussion.