public boolean previousPage() throws SQLException {
       throw new UnsupportedOperationException();
    }
Retrieves the data present in the page prior to the page from where it is
called.
@return boolean value true if it retrieves the previous page, flase if it
        is on the first page.
@throws SQLException if it is called before populate is called or ResultSet
        is of type <code>ResultSet.TYPE_FORWARD_ONLY</code> or if an error
        occurs.
src/main/java/org/replicadb/rowset/sun/rowset/internal/SyncResolverImpl.java