private void setSuff(String s, int len) {
    word.setLength(j + 1);
    for (int l = 0; l < len; l++) {
      word.unsafeWrite(s.charAt(l));
    }
    k = j + len;
  }
*
YCS: this was the one place where lookup was not followed by return.
So restructure it. if ((j>0)&&(lookup(word.toString())) &&
!((word.charAt(j) == 's') && (word.charAt(j-1) == 's'))) return;
***
linguistics/src/main/java/com/yahoo/language/simple/kstem/KStemmer.java