code: static String getSystemProperty(final String key) {
          final SecurityManager sm = System.getSecurityManager();
  
          if (sm != null) {
              return AccessController.doPrivileged(new PrivilegedAction<String>() {
                  public String run() {
                      return System.getProperty(key);
                  }
              });
          } else {
              return System.getProperty(key);
          }
      }
docs: Returns a system property value using the specified <code>key</code>.
  
  @param key
  @return