code: public static KeyStore createTrustStore(final Reader certReader) throws IOException, CertificateException,
              KeyStoreException, NoSuchAlgorithmException {
          try (PEMParser pemParser = new PEMParser(certReader)) {
  
              KeyStore trustStore = KeyStore.getInstance("JKS");
              trustStore.load(null);
  
              int index = 1;
              Object pemCert;
  
              while ((pemCert = pemParser.readObject()) != null) {
                  Certificate caCertificate = new JcaX509CertificateConverter()
                          .setProvider(BouncyCastleProvider.PROVIDER_NAME)
                          .getCertificate((X509CertificateHolder) pemCert);
                  trustStore.setCertificateEntry("ca-" + index, caCertificate);
                  index++;
              }
  
              return trustStore;
          }
      }
docs: "ca.pem" from Reader