code: public KeyManagerConfigurer keyPassword(String key, String password) {
          if (keyPasswords == null) {
              keyPasswords = new HashMap<>();
          }
          keyPasswords.put(key, password);
          return this;
      }
docs: Alternative to {@link #keyPasswords} when only 1 (one) key is present in the {@link KeyStore}.
  <p>
  Alternatively use property:
  <pre>
  saml.sso.key-manager.key-passwords
  </pre>
  </p>
  
  @param key      the key name.
  @param password the key password.
  @return this configurer for further customization