code: public List<PKIXCertPathChecker> getCertPathCheckers() {
          List<PKIXCertPathChecker> tmpList = new ArrayList<PKIXCertPathChecker>();
          for (PKIXCertPathChecker ck : certPathCheckers) {
              tmpList.add((PKIXCertPathChecker)ck.clone());
          }
          return Collections.unmodifiableList(tmpList);
      }
docs: Returns the {@code List} of certification path checkers.
  The returned {@code List} is immutable, and each
  {@code PKIXCertPathChecker} in the {@code List} is cloned
  to protect against subsequent modifications.
  
  @return an immutable {@code List} of
  {@code PKIXCertPathChecker}s (may be empty, but not
  {@code null})
  @see #setCertPathCheckers