code: public static boolean isEqual(String s1, String s2, int modifier) {
          if (s1 == s2) return true;
          if (null == s1) {
              return s2 == null;
          }
          if (null == s2) {
              return false;
          }
          if ((modifier & IGNORESPACE) != 0) {
              s1 = s1.trim();
              s2 = s2.trim();
          }
          if ((modifier & IGNORECASE) != 0) {
              return s1.equalsIgnoreCase(s2);
          } else {
              return s1.equals(s2);
          }
      }
docs: Determine whether two string instance is equal based on
  the modifier passed in.
  <p/>
  <p>
  is 2 strings equal case insensitive?
  <code>S.isEqual(s1, s2, S.IGNORECASE)</code>
  </p>
  <p/>
  <p>
  is 2 strings equals case and space insensitive?
  <code>S.isEqual(s1, s2, S.IGNORECASE & S.IGNORESPACE)</code>
  </p>
  
  @param s1
  @param s2
  @param modifier
  @return true if s1 equals s2