@Override
    public SegmentInputStreamProvider getSegmentInputStreamProvider(final String streamTypeName) {
        return inputStreamMap.computeIfAbsent(streamTypeName, k -> {
            final InternalSource source = getChild(k);
            if (source == null) {
                return null;
            }
            return new SegmentInputStreamProvider(source, k);
        });
    }
Creates a new file system stream source.

@return A new file system source.
stroom-data/stroom-data-store-impl-fs/src/main/java/stroom/data/store/impl/fs/FsSource.java