fixes #75: handle the idp url already having a query parameter

Author: miszobi

core/src/main/java/com/onelogin/saml2/util/Util.java

@@ -570,7 +570,7 @@ public static void sendRedirect(HttpServletResponse response, String location, M
 		String target = location;
 
 		if (!parameters.isEmpty()) {
-			Boolean first = true;
+			boolean first = !location.contains("?");
 			for (Map.Entry<String, String> parameter : parameters.entrySet())
 			{
 				if (first) {

core/src/test/java/com/onelogin/saml2/test/util/UtilsTest.java

@@ -2107,4 +2107,16 @@ public void testQuery() throws XPathExpressionException, URISyntaxException, IOE
 		Node assertion_2 = assertionNodes_2.item(0);
 		assertEquals("saml2:Assertion", assertion_2.getNodeName());
 	}
+
+	@Test
+	public void sendRedirectToShouldHandleUrlsWithQueryParams() throws Exception {
+		// having
+		final HttpServletResponse response = mock(HttpServletResponse.class);
+
+		// when
+		Util.sendRedirect(response, "https://sso.connect.pingidentity.com/sso/idp/SSO.saml2?idpid=ffee-aabbb", Collections.singletonMap("SAMLRequest", "data"));
+
+		// then
+		verify(response).sendRedirect("https://sso.connect.pingidentity.com/sso/idp/SSO.saml2?idpid=ffee-aabbb&SAMLRequest=data");
+	}
 }