/**
 * Executes HEAD request to get redirects.
 * Throws IllegalStateException in case of status code outside of "200-207"
 * @param from URI to issue HEAD request
 * @return List of redirects. {@code null} if there are no redirects.
 */
public List<URI> getRedirects(URI from)
{
    try
    {
        HttpClientContext httpContext = HttpClientContext.create();
        httpClient.doHttpHead(from, httpContext).verifyStatusCodeInRange(HttpStatus.SC_OK,
                HttpStatus.SC_MULTI_STATUS);
        return httpContext.getRedirectLocations();
    }
    catch (IOException | ExternalServiceException e)
    {
        String exceptionMsg;
        if (e.getCause() instanceof CircularRedirectException)
        {
            exceptionMsg = e.getCause().getMessage() + " Circular redirects are forbidden by default. "
                    + "To allow them, please set property "
                    + "'http.redirects-provider.circular-redirects-allowed=true'";
        }
        else
        {
            exceptionMsg = e.getMessage();
        }
        throw new IllegalStateException(exceptionMsg, e);
    }
}
 

@Test
public void shouldUpdateErrorMessageAndRethrowAsIllegalStateExceptionInCaseOfCircularRedirectException()
        throws IOException
{
    ClientProtocolException clientProtocolException = new ClientProtocolException(
            new CircularRedirectException("Circular reference"));
    when(httpClient.doHttpHead(URI_EXAMPLES, httpClientContext)).thenThrow(clientProtocolException);
    IllegalStateException illegalStateException = assertThrows(IllegalStateException.class,
        () -> redirectsProvider.getRedirects(URI_EXAMPLES));
    assertEquals("Circular reference Circular redirects are forbidden by default. To allow them, please set "
                    + "property 'http.redirects-provider.circular-redirects-allowed=true'",
            illegalStateException.getMessage());
}