code: @Test public void testRequestTargetHostFallback() throws Exception {
    HttpContext context=new BasicHttpContext(null);
    BasicHttpRequest request=new BasicHttpRequest("GET","/");
    InetAddress address=Mockito.mock(InetAddress.class);
    Mockito.when(address.getHostName()).thenReturn("somehost");
    HttpInetConnection conn=Mockito.mock(HttpInetConnection.class);
    Mockito.when(conn.getRemoteAddress()).thenReturn(address);
    Mockito.when(conn.getRemotePort()).thenReturn(1234);
    context.setAttribute(ExecutionContext.HTTP_TARGET_HOST,null);
    context.setAttribute(ExecutionContext.HTTP_CONNECTION,conn);
    RequestTargetHost interceptor=new RequestTargetHost();
    interceptor.process(request,context);
    Header header=request.getFirstHeader(HTTP.TARGET_HOST);
    Assert.assertNotNull(header);
    Assert.assertEquals("somehost:1234",header.getValue());
  }
  