add comment to tests cases

Author: enqueue

jdbc-v2/src/test/java/com/clickhouse/jdbc/internal/JdbcConfigurationTest.java

@@ -210,6 +210,7 @@ public Object[][] createInvalidConnectionURLs() {
             { "jdbc:clickhouse://foo.bar?x&y=z" },
             { "jdbc:clickhouse://foo.bar?x==&y=z" },
             { "jdbc:clickhouse://localhost?☺=value1" },
+            // multiple endpoints are invalid
             { "jdbc:clickhouse://foo,bar" },
             { "jdbc:clickhouse://foo,bar.com:8123" },
         };