[jdbc-v2] User-Agent wraps detected frameworks in double parentheses: ((apache.spark))

The double group comes from two places in jdbc-v2: Driver.FrameworksDetection.getFrameworksDetected() in jdbc-v2/src/main/java/com/clickhouse/jdbc/Driver.java wraps each name in parentheses, and ConnectionImpl in jdbc-v2 wraps the joined result again. Remove the per-name wrapping in the jdbc-v2 copy only, leaving DriverV1.FrameworksDetection in jdbc-v1 unchanged. Done when a stack containing org.apache.spark yields one group like (apache.spark), and a stack with no framework still yields no group. A test in an org.apache.spark package must reset the static frameworksDetected field first.

Description

When jdbc-v2 detects a framework on the call stack (apache.spark, apache.flink, apache.nifi), it adds the framework names to the User-Agent header inside two levels of parentheses:

jdbc-v2/0.12.0-rc1-SNAPSHOT ((apache.spark)) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT (Linux; jvm:17.0.20.1) Apache-HttpClient/5.6.4

With two frameworks on the stack, each name gets its own inner group:

jdbc-v2/0.12.0-rc1-SNAPSHOT ((apache.flink); (apache.spark)) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT (Linux; jvm:17.0.20.1) Apache-HttpClient/5.6.4

Nested comments are valid HTTP (RFC 9110), so requests do not fail. But the header is read by tools that parse system.query_log.http_user_agent (see #2775), and a single comment group is the shape that the rest of the header uses.

Root cause

Two places add parentheses:

1. Driver.FrameworksDetection.getFrameworksDetected() wraps each name: inferredFrameworks.add(String.format("(%s)", framework)), then joins with "; ".
   https://github.com/ClickHouse/clickhouse-java/blob/5392b642e5ca0375a77b8cc0f15b29b97a8f772f/jdbc-v2/src/main/java/com/clickhouse/jdbc/Driver.java#L50-L55
2. ConnectionImpl wraps the result again: clientName += " (" + detectedFrameworks + ")".
   https://github.com/ClickHouse/clickhouse-java/blob/5392b642e5ca0375a77b8cc0f15b29b97a8f772f/jdbc-v2/src/main/java/com/clickhouse/jdbc/ConnectionImpl.java#L101-L107

FrameworksDetection is the same code as DriverV1.FrameworksDetection in jdbc-v1. jdbc-v1 appends the result directly to the product name, with no outer group, so there the inner parentheses are the only group:
https://github.com/ClickHouse/clickhouse-java/blob/5392b642e5ca0375a77b8cc0f15b29b97a8f772f/clickhouse-jdbc/src/main/java/com/clickhouse/jdbc/internal/ClickHouseConnectionImpl.java#L287-L291
jdbc-v2 kept the per-name parentheses and added an outer group, so the names are wrapped twice.

Suggested fix

In jdbc-v2 only, remove one level. For example, add the plain name in Driver.FrameworksDetection (inferredFrameworks.add(framework)) and keep the outer group in ConnectionImpl. Result:

• one framework: jdbc-v2/<v> (apache.spark) clickhouse-java-v2/<v> ...
• two frameworks: jdbc-v2/<v> (apache.flink; apache.spark) clickhouse-java-v2/<v> ...

Cases that must not change:

• No framework on the stack: no group (today: jdbc-v2/<v> clickhouse-java-v2/<v> ...).
• jdbc-v1 (DriverV1.FrameworksDetection): it has no outer group, so it needs its per-name parentheses.

A unit test can call Driver.FrameworksDetection.getFrameworksDetected() from a class in an org.apache.spark.* package. The result is cached in a static field, so the test must reset FrameworksDetection.frameworksDetected (package-private) first.

Related: #3213 (open) changes the client-v2 part of the header to the standard format for #3202. It does not change the jdbc-v2 framework group and says this is a separate issue. A maintainer could also decide to move the frameworks into the new client_metadata key/value pairs. That changes the jdbc-v2 output and needs a key name, so it is a design decision, not part of this bug.

Steps to reproduce

1. Put a class in a package whose name contains apache.spark (for example org.apache.spark.repro) and open a jdbc-v2 connection from it.
2. Run a query that has a unique marker, then SYSTEM FLUSH LOGS.
3. Read http_user_agent for that query from system.query_log.

Error Log or Exception StackTrace

No exception. Observed http_user_agent values (one JVM per row, because detection result is cached per JVM):

[spark on stack]                    jdbc-v2/0.12.0-rc1-SNAPSHOT ((apache.spark)) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT (Linux; jvm:17.0.20.1) Apache-HttpClient/5.6.4
[spark, client_name=my-app/1.0]     my-app/1.0 jdbc-v2/0.12.0-rc1-SNAPSHOT ((apache.spark)) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT (Linux; jvm:17.0.20.1) Apache-HttpClient/5.6.4
[spark -> flink on stack]           jdbc-v2/0.12.0-rc1-SNAPSHOT ((apache.flink); (apache.spark)) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT (Linux; jvm:17.0.20.1) Apache-HttpClient/5.6.4
[no framework on stack]             jdbc-v2/0.12.0-rc1-SNAPSHOT clickhouse-java-v2/0.12.0-rc1-SNAPSHOT (Linux; jvm:17.0.20.1) Apache-HttpClient/5.6.4

Expected Behaviour

One comment group with the framework names:

jdbc-v2/0.12.0-rc1-SNAPSHOT (apache.spark) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT ...
jdbc-v2/0.12.0-rc1-SNAPSHOT (apache.flink; apache.spark) clickhouse-java-v2/0.12.0-rc1-SNAPSHOT ...

Code Example

package org.apache.spark.repro;   // "apache.spark" in the stack trace triggers detection

import java.sql.*;
import java.util.*;

public class SparkApp {
    public static void main(String[] args) throws Exception {
        Properties p = new Properties();
        p.setProperty("user", "default");
        p.setProperty("password", "<password>");
        String marker = "ua_probe_" + UUID.randomUUID().toString().replace("-", "");
        try (Connection c = new com.clickhouse.jdbc.Driver().connect("jdbc:clickhouse://localhost:8123/default", p);
             Statement s = c.createStatement()) {
            s.executeQuery("SELECT '" + marker + "'").close();
            s.execute("SYSTEM FLUSH LOGS");
            try (ResultSet rs = s.executeQuery("SELECT http_user_agent FROM system.query_log"
                    + " WHERE type = 'QueryFinish' AND query LIKE '%" + marker + "%'"
                    + " AND query NOT LIKE '%query_log%' LIMIT 1")) {
                rs.next();
                System.out.println(rs.getString(1));
                // prints: jdbc-v2/<v> ((apache.spark)) clickhouse-java-v2/<v> (...)
            }
        }
    }
}

For the two-framework case, call the same code from a class in org.apache.flink.repro that SparkApp calls.

Configuration

Client Configuration

// defaults; framework detection is enabled by default

Environment

• Cloud
• Client version: jdbc-v2 0.12.0-rc1-SNAPSHOT, built from main at 5392b642e5ca0375a77b8cc0f15b29b97a8f772f
• Language version: Java 17.0.20.1
• OS: Linux

ClickHouse Server

• ClickHouse Server version: 26.9.1.1629
• ClickHouse Server non-default settings, if any: none relevant
• CREATE TABLE statements for tables involved: none (SELECT '<marker>' only)

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Found by automated analysis (Polyglot AI) while working on #3202. Verified by running the code above against a live ClickHouse server, not only by reading the code.