TransferFsImage#doGetUrl downloads files from the specified url and stores them in the specified storage location.
HDFS-4025 plans to synchronize the log segments in JournalNodes. If a log segment is missing from a JN, the JN downloads it from another JN which has the required log segment. We need TransferFsImage#doGetUrl and TransferFsImage#receiveFile to accomplish this.
So we propose to move the said functions to a Utility class so as to be able to use it for JournalNode syncing as well, without duplication of code.