CommitLogArchiver.maybeRestoreArchive() throws a RuntimeException when it failed to list a directory

Dear Cassandra developers, we are developing a tool to detect exception-related bugs in Java. Our prototype has spotted the following throw statement whose exception class and error message indicate different error conditions.

Version: Cassandra-3.11 (commit: 123113f7b887370a248669ee0db6fdf13df0146e) 

File: CASSANDRA-ROOT/src/java/org/apache/cassandra/db/commitlog/CommitLogArchiver.java

Line: 225

throw new RuntimeException("Unable to list directory " + dir);

RuntimeException is usually used to represent errors in the program logic (think of one of its subclasses, NullPointerException), while the error message indicates that maybeRestoreArchive() failed to list a directory. This mismatch could be a problem. For example, the callers may miss the possibility that maybeRestoreArchive() can fail to list a directory because it does not throw any IOException. Or, the callers trying to handle other RuntimeException may accidentally (and incorrectly) handle the directory listing failure.