The java.regex.Pattern engine has an optimized node Ques to represent the quantifier of type 'X?'.
It would be beneficial, if the same optimized node was used for 'X{0,1}', which is essentially the same.

Currently, a less efficient construct is used for the later expression:

$java java.util.regex.PrintPattern 'X?'
   Pattern: X?
     0: <Start>
     1: <Ques GREEDY>
     2: <BmpCharProperty>
         </Ques>
     3: <END>

$java java.util.regex.PrintPattern 'X{0,1}'
   Pattern: X{0,1}
     0: <Start>
     1: <Curly GREEDY {0, 1}>
     2: <BmpCharProperty>
         </Curly>
     3: <END>