code: @Override
      public FileSystem getFileSystem(final URI uri) {
  
          // Get open FS
          final FileSystem fs = this.createdFileSystems.get(uri.getHost());
  
          // If not already created
          if (fs == null) {
              throw new FileSystemNotFoundException("Could not find an open file system with URI: " + uri.toString()
                  + "; try creating a new file system?");
          }
  
          // Return
          return fs;
      }
docs: {@inheritDoc}
  
  @see java.nio.file.spi.FileSystemProvider#getFileSystem(java.net.URI)