A DESCRIPTION OF THE PROBLEM :
The lookbehind section of a pattern can match text that comes before the start parameter

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the code from "Source code for an executable test case"

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
false

---------- BEGIN SOURCE ----------
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Test {
    public static void main(String[] args) {
        Pattern pattern = Pattern.compile("(?<=te)st");
        Matcher matcher = pattern.matcher("test");
        System.out.println(matcher.find(2));
    }
}
---------- END SOURCE ----------

FREQUENCY : always