code: public void setSystemProperty(String name, String value) throws Exception {
          final ModelNode request = createRequest(ADD, Address.root().add(SYSTEM_PROPERTY, name));
          request.get(VALUE).set(value);
          final ModelNode response = execute(request);
          if (!isSuccess(response)) {
              throw new FailureException(response, "Failed to set system property [" + name + "]");
          }
      }
docs: Set a runtime system property in the JVM that is managed by JBossAS.
  
  @param name system property name to set
  @param value the new value of the system property
  @throws Exception any error