Core: LowLevelHttpResponse not disconnected when HttpResponse construction throws RuntimeException

google-http-client/src/main/java/com/google/api/client/http/HttpRequest.java から始め、HttpRequest.execute() とその finally ブロックに注目してください。getContentEncoding() が例外をスローする LowLevelHttpResponse で失敗を再現し、その後 testExecute_disconnectOnResponseConstructionFailure を実行してください。レスポンスの構築に失敗したときに低レベルレスポンスが切断され、回帰テストに合格すれば完了です。

Environment details:

1. Core — HttpRequest.execute() in google-http-client
2. OS type and version: Any (not OS-specific)
3. Java version: Any (reproduces on Java 8+)
4. google-http-client version(s): reproducible on current main

Steps to reproduce:

1. Implement a LowLevelHttpResponse whose getContentEncoding() throws a RuntimeException.
2. Execute an HttpRequest against that transport.
3. Catch the RuntimeException from execute().
4. Observe disconnect() was never called on the low-level response.

Code example:

MockLowLevelHttpResponse failingResponse = new MockLowLevelHttpResponse() {
  @Override
  public String getContentEncoding() {
    throw new RuntimeException("simulated failure");
  }
};

HttpTransport transport = new MockHttpTransport() {
  @Override
  public LowLevelHttpRequest buildRequest(String method, String url) throws IOException {
    return new MockLowLevelHttpRequest().setResponse(failingResponse);
  }
};

HttpRequest req = transport.createRequestFactory()
    .buildGetRequest(new GenericUrl("http://example.com"));

try {
  req.execute();
} catch (RuntimeException e) {
  // failingResponse.isDisconnected() == false  <-- BUG: socket leaked
}

Stack trace:
None — silent resource leak, not a crash. The RuntimeException propagates as expected; the
bug is that execute()'s finally block never calls LowLevelHttpResponse#disconnect() here.

External references:

• HttpRequest#execute(): google-http-client/src/main/java/com/google/api/client/http/HttpRequest.java

Any additional information:
Under sustained error conditions, leaked connections accumulate until the pool is exhausted,
risking DoS/thread starvation. Pre-existing bug, unrelated to security hardening — found
opportunistically during a security audit of this file.

Proposed fix — in execute()'s finally block, add a guarded disconnect():

} finally {
  if (!responseConstructed && lowLevelHttpResponse != null) {
    try {
      InputStream c = lowLevelHttpResponse.getContent();
      if (c != null) c.close();
    } catch (IOException ignored) {}
    try {
      lowLevelHttpResponse.disconnect();
    } catch (IOException ignored) {}
  }
}

Regression test testExecute_disconnectOnResponseConstructionFailure included in the
accompanying PR.