HBaseObjectStoreSemantics, as a wrapper of object store file system implementation, currently extends FileSystem itself. There is no straightforward way to expose its wrapped files system. However, some tooling would need to operate using the wrapped object store file systems, for e.g. S3GuardTool is expecting the file system implementation is S3A so it can access the metadata store easily. A simple S3GuardTool against HBOSS will get confusing error like "s3a://mybucket is not a S3A file system".
Let's make HBaseObjectStoreSemantics a FilterFileSystem so that places like S3GuardTool can use getRawFilesSystem() to retrieve the wrapped file system. Doing this should not break the contract of HBOSS contract.