GUACAMOLE-220: Manually recurse through the group membership graph if the database engine does not support recursive queries.

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLEnvironment.java

@@ -225,5 +225,10 @@ public class MySQLEnvironment extends JDBCEnvironment {
     public String getMySQLPassword() throws GuacamoleException {
         return getRequiredProperty(MySQLGuacamoleProperties.MYSQL_PASSWORD);
     }
-    
+
+    @Override
+    public boolean isRecursiveQuerySupported() {
+        return false; // Only very recent versions of MySQL / MariaDB support recursive queries through CTEs
+    }
+
 }