public String stem(String term) {
    boolean changed = stem(term.toCharArray(), term.length());
    if (!changed) return term;
    return asString();
  }
*
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