code: @Nonnegative
    public static int readFully (@Nonnull final InputStream aIS, @Nonnull final byte [] aBuffer) throws IOException
    {
      return readFully (aIS, aBuffer, 0, aBuffer.length);
    }
docs: Read the whole buffer from the input stream.
  
  @param aIS
  The input stream to read from. May not be <code>null</code>.
  @param aBuffer
  The buffer to write to. May not be <code>null</code>. Must be &ge;
  than the content to be read.
  @return The number of read bytes
  @throws IOException
  In case reading fails