There will be some attention paid to insecure URLs used for retrieval of build dependencies. While our build does not have direct exposure to this we do have some insecure URLs pointing to secondary resources like JIRA, mailing list archives, hbase.apache.org, and the online book. Make these https too.
I left the license header text alone, although there is a URL to the ASL 2 license embedded there. If we are going to update that, let's do that as a separate task because just about every file is going to be touched.