question: private String composeOneStep ( String input ) { int len = countChars ( input , 0 , 2 ) ; String firstTwoCharacters = input . substring ( 0 , len ) ; String result = Normalizer . normalize ( firstTwoCharacters , Normalizer . Form . NFC ) ; if ( result . equals ( firstTwoCharacters ) ) return null ; else { String remainder = input . substring ( len ) ; return result + remainder ; } }
target:  Attempts to compose input by combining the first character with the first combining mark following it. Returns a String that is the composition of the leading character with its first combining mark followed by the remaining combining marks. Returns null if the first two characters cannot be further composed.