$/**$

$*$ Find the most common character in str$.$

$*$ You could use a HashMap that maps a Character key to an Int value to represent how many times a Character has

$*$ been spotted.

$*$ @param str A String.

$*$ @return the most common character within str$.$

$*/$

$$ public char recurringChar$($String str$)\{$

$$ return $\text{'}\text{'}$;

$\}$