code: @Nonnull
    public static String getImplodedNonEmpty (@Nonnull final String sSep,
                                              @Nullable final String [] aElements,
                                              @Nonnegative final int nOfs,
                                              @Nonnegative final int nLen)
    {
      return getImplodedMappedNonEmpty (sSep, aElements, nOfs, nLen, Function.identity ());
    }
docs: Get a concatenated String from all elements of the passed array, separated by
  the specified separator string. This the very generic version of
  {@link #getConcatenatedOnDemand(String, String, String)} for an arbitrary
  number of elements.
  
  @param sSep
  The separator to use. May not be <code>null</code>.
  @param aElements
  The container to convert. May be <code>null</code> or empty.
  @param nOfs
  The offset to start from.
  @param nLen
  The number of elements to implode.
  @return The concatenated string.