Issue #4138 - only warn if metadata issuer is not consistent with config

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>

jetty-openid/src/main/java/org/eclipse/jetty/security/openid/OpenIdConfiguration.java

@@ -107,7 +107,7 @@ public class OpenIdConfiguration extends ContainerLifeCycle implements Serializa
                 throw new IllegalArgumentException("token_endpoint");
 
             if (!Objects.equals(discoveryDocument.get("issuer"), issuer))
-                throw new IllegalArgumentException("The provider in the metadata is not correct.");
+                LOG.warn("The issuer in the metadata is not correct.");
         }
     }