implemented password reset flow

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.oidc.datastore.file/src/main/java/de/srsoftware/oidc/datastore/file/FileStore.java

@@ -81,10 +81,9 @@ public class FileStore implements AuthorizationService, ClientService, SessionSe
 
 	@Override
 	public Optional<User> forToken(String id) {
-		AccessToken token = accessTokens.get(id);
+		AccessToken token = accessTokens.remove(id);
 		if (token == null) return empty();
 		if (token.valid()) return Optional.of(token.user());
-		accessTokens.remove(token.id());
 		return empty();
 	}