code: public static void setChar (@Nonnull final CharSequence aSeq, final int nIndex, @Nonnull final Codepoint aCodepoint)
    {
      setChar (aSeq, nIndex, aCodepoint.getValue ());
    }
docs: Set the character at a given location, automatically dealing with surrogate
  pairs
  
  @param aSeq
  source sequence
  @param nIndex
  index
  @param aCodepoint
  codepoint to be set