Method appendLog

ZezeJava/ZezeJavaTest/src/SimpleRaft/Raft.java:54–54

(@NotNull Log log)

		@Nullable Log getLogByKey(long key); // return null if not exist

		boolean appendLog(@NotNull Log log); // return false if this log(key) is already appended

		void appendLogs(@NotNull Log @NotNull [] logs); // ignore already appended log(key)s