code: public void setUseProxyChainAuth(boolean useProxyChainAuth) {
          if (useProxyChainAuth && (getProxyChainUserName() == null || getProxyChainUserName().isEmpty())) {
              return;
          }
  
          this.useProxyChainAuth = useProxyChainAuth;
          getConfig().setProperty(USE_PROXY_CHAIN_AUTH_KEY, this.useProxyChainAuth);
      }
docs: Sets whether or not the outgoing connections should use the proxy authentication credentials set.
  <p>
  <strong>Note:</strong> The call to this method has no effect if set to use the credentials but the credentials were not
  previously set.
  
  @param useProxyChainAuth {@code true} if outgoing connections should use the proxy authentication credentials set,
  {@code false} otherwise.
  @since 2.3.0
  @see #isUseProxyChainAuth()
  @see #setUseProxyChain(boolean)
  @see #setProxyChainUserName(String)
  @see #setProxyChainPassword(String)
  @see #setProxyChainRealm(String)