@Nullable
    public InputStream openForRead(final Folder folder, final String subfolderAndName) {
        if (folder == null || subfolderAndName == null) {
            return null;
        }
        final FileInformation fi = getFileInfo(folder, subfolderAndName);
        if (fi != null) {
            return openForRead(fi.uri);
        }
        return null;
    }
Opens a file for read identified relatively to a root Folder and its name.
Name may contain optionally a subfolder structure, see {@link #getParentFolderAndFileInfo(Folder, String)} for details.
Remember to close stream after usage! Returns null if Uri can't be opened for reading.
main/src/main/java/cgeo/geocaching/storage/ContentStorage.java