fix: suppress OkHttp default User-Agent header on outbound requests

[chrismParticle]

Summary

• Adds a UserAgentInterceptor (network interceptor) to ApiClient that strips OkHttp's default User-Agent header (okhttp/<version>) after BridgeInterceptor injects it
• Wired in both createDefaultAdapter() and configureFromOkclient() so all construction paths are covered
• Caller-supplied User-Agent values (set via a custom OkHttp interceptor) are detected and passed through unchanged
• This resolves cases where mParticle was enriching device_info.http_header_user_agent with a meaningless library-identifier string

Version

Changelog entry added for 2.8.0.

Test plan

• New test class ApiClientUserAgentTest covers three cases using MockWebServer: default path (no UA), caller override preserved, and configureFromOkclient path
• ./gradlew test — 9 tests, all passing
• Manually verified against mParticle Live Stream: batch without UA shows no device_info.http_header_user_agent; batch with User-Agent: my_app shows my_app correctly

Notes

• Uses addNetworkInterceptor (not addInterceptor) — required because OkHttp's BridgeInterceptor runs between application and network interceptors and re-injects the default UA if the header is absent at the application layer
• RateLimitInterceptor is unchanged
• No public API surface changes

🤖 Generated with Claude Code

[cursor]

PR Summary

Medium Risk
Changes outbound HTTP header behavior by stripping OkHttp’s default User-Agent, which could affect any downstream systems that relied on that value, though caller-supplied headers are preserved and behavior is covered by new tests.

Overview
Suppresses OkHttp’s default User-Agent on SDK requests. ApiClient now installs a network UserAgentInterceptor that removes User-Agent: okhttp/<version> after OkHttp injects it, while leaving any caller-provided User-Agent untouched (including when using configureFromOkclient).

Adds MockWebServer-backed tests covering default/no-override and override cases, documents the new behavior in README, and records the fix in the 2.8.0 changelog entry.

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