docs: public Key retrievePublicKey() throws IOException {
          PublicKey publicKey = null;
  
          try {
              X509Certificate cert = retrieveCertificate();
              publicKey = cert.getPublicKey();
              return publicKey;
          } catch (java.net.MalformedURLException me) {
              if (tc.isDebugEnabled())
                  Tr.debug(tc, "Exception opening keystore.", me.getMessage());
              throw new IOException(me.getMessage());
          } catch (java.io.IOException ioe) {
              if (tc.isDebugEnabled())
                  Tr.debug(tc, "Exception opening keystore.", ioe.getMessage());
              throw new IOException(ioe.getMessage());
  
          }
      }