#24284 [Java][apache-httpclient] Apply connect timeout to requests, add read timeout support

Fixes #24269.

For the Java client with library=apache-httpclient, ApiClient.setConnectTimeout(int) stored the value in a connectionTimeout field that was never read again, so the setter was a silent no-op: the client fell back to Apache HttpClient 5's own defaults (3-minute connect timeout, unbounded response wait).

Changes

• invokeAPI() now builds a per-request RequestConfig from the configured timeouts and sets it on the HttpClientContext, so setConnectTimeout(ms) actually bounds the TCP connect time, consistent with the other Java libraries (okhttp-gson, native).
• Added symmetric getReadTimeout()/setReadTimeout(ms) mapped to the response timeout, as suggested in the issue (mirrors the okhttp-gson naming).
• A value of 0 (the default) leaves the underlying client's configuration untouched.

The per-request RequestConfig approach was chosen over rebuilding the client with a PoolingHttpClientConnectionManager/ConnectionConfig because:

• ConnectionConfig only exists since httpclient5 5.2, while the Gradle template still ships 5.1.3 (RequestConfig#setConnectTimeout(Timeout) exists since 5.0 and is honored in all 5.x versions, taking precedence over connection-manager defaults in 5.3+);
• it preserves a user-supplied custom CloseableHttpClient (constructor or setHttpClient) instead of silently discarding it.

Tests

Added ApiClientTest to the apache-httpclient petstore sample:

• getter/setter round-trips for both timeouts;
• a regression test that a request against a socket that accepts but never responds fails after the configured 500 ms read timeout (verified: 0.52 s elapsed) instead of hanging forever;
• a regression test that a connect to a non-routable TEST-NET-1 address fails within bounds instead of taking Apache's 3-minute default.

All 136 test classes in the sample pass; the echo_api and jackson3 samples were regenerated (./bin/generate-samples.sh bin/configs/java-apache-httpclient*.yaml) and compile.

PR checklist

• Read the contribution guidelines.
• Run the following to build the project and update samples: ./bin/generate-samples.sh bin/configs/java-apache-httpclient*.yaml (only the apache-httpclient templates changed; no doc changes, so export_docs_generators.sh produces no diff).
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @martin-mfg

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Summary by cubic

Applies per-request connect and read timeouts in the Java apache-httpclient client to prevent hangs and make setConnectTimeout effective. Preserves defaults from a custom CloseableHttpClient. Fixes #24269.

• Bug Fixes

  • Applies setConnectTimeout(ms) per request to bound TCP connect time.
  • Builds per-request RequestConfig from the underlying client's defaults (via Configurable); 0 uses client defaults.
  • Rejects negative values in setConnectTimeout()/setReadTimeout().

• New Features

  • Added getReadTimeout()/setReadTimeout(ms) to control response wait time.
  • Works with httpclient5 5.1.x+; per-request config is compatible across versions.