Refactor and cleanup

* simplify AttributeEndpointsResourceProvider
* improve explanation of properties in AdminUiPage
* add example for mailing lists and map endpoint
* better explain configuration and operation of provider in main readme
* adjust the Keycloak realm
* Add unit test for endpoint class

testing/client-test-export-mailing-lists.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+
+#
+# Use curl to run a test export of Dooris ssh keys
+#
+
+set -e
+
+ACCESS_TOKEN="$(curl -s --request POST \
+  --url http://localhost:8080/realms/testing/protocol/openid-connect/token \
+  --header 'content-type: application/x-www-form-urlencoded' \
+  --data scope=openid \
+  --data client_id=export-mailing-list-addresses \
+  --data client_secret=export-mailing-list-addresses-secret \
+  --data grant_type=client_credentials | jq --raw-output .access_token -)"
+
+echo "chaos@"
+curl -s --request GET \
+  --url http://localhost:8080/realms/testing/attribute-endpoints-provider/export/mailing-list-addresses-chaos \
+  --header "authorization: Bearer ${ACCESS_TOKEN}" \
+  --header "content-type: application/json" | jq . -
+
+echo "intern@"
+curl -s --request GET \
+  --url http://localhost:8080/realms/testing/attribute-endpoints-provider/export/mailing-list-addresses-intern \
+  --header "authorization: Bearer ${ACCESS_TOKEN}" \
+  --header "content-type: application/json" | jq . -