code: public void setSubjectPublicKeyAlgID(String oid) throws IOException {
          if (oid == null) {
              subjectPublicKeyAlgID = null;
          } else {
              subjectPublicKeyAlgID = new ObjectIdentifier(oid);
          }
      }
docs: Sets the subjectPublicKeyAlgID criterion. The
  {@code X509Certificate} must contain a subject public key
  with the specified algorithm. If {@code null}, no
  subjectPublicKeyAlgID check will be done.
  
  @param oid The object identifier (OID) of the algorithm to check
  for (or {@code null}). An OID is represented by a
  set of nonnegative integers separated by periods.
  @throws IOException if the OID is invalid, such as
  the first component being not 0, 1 or 2 or the second component
  being greater than 39.
  
  @see #getSubjectPublicKeyAlgID