Migrate Java Random to SecureRandom

[gitar-bot-staging]

Migrate OkHttp from Random to SecureRandom for Enhanced Cryptographic Security

Description

This PR comprehensively migrates OkHttp from standard Random implementations to cryptographically secure SecureRandom implementations across all security-sensitive operations. The migration includes extensive performance monitoring tools and documentation to ensure security improvements don't compromise performance.

Motivation

• Security Enhancement: Standard Random implementations are not cryptographically secure and can be predictable, creating vulnerabilities in security-sensitive operations like WebSocket frame masking, OAuth token generation, and SSL/TLS certificate handling
• Compliance: Using SecureRandom aligns with security best practices for cryptographic operations and helps meet security compliance requirements

Key Changes

• Core Migration: Converted all Random usage to SecureRandom across OkHttp components including WebSocket handling, connection pooling, and OAuth session management
• Performance Monitoring: Added comprehensive performance monitoring utilities (RandomBenchmark, RandomMigrationMonitor, RandomMigrationUtility) to measure and optimize the security vs performance trade-offs
• Testing Enhancement: Introduced property-based testing with jqwik to ensure robust validation of the migration
• Documentation: Created detailed migration guide with performance optimization strategies

Impact

Files Changed (23 files, +2,101/-23 lines)

Core Changes

• okhttp3/OkHttpClient.kt - Updated client-level random generation
• okhttp3/internal/connection/RealConnectionPool.kt - Secured connection pool randomization
• okhttp3/internal/ws/RealWebSocket.kt & WebSocketWriter.kt - Secured WebSocket frame masking
• okhttp3/slack/OAuthSessionFactory.java - Secured OAuth session generation
• okhttp3/sample/SampleServer.java - Updated sample implementations

New Performance & Testing Infrastructure

• docs/random_migration_guide.md - Comprehensive migration documentation
• internal/performance/RandomBenchmark.kt - Performance comparison tools
• internal/performance/RandomMigrationMonitor.kt - Real-time monitoring
• internal/performance/RandomMigrationUtility.kt - Migration utilities
• Multiple property-based tests for validation

Test Plan

• ✅ All existing tests pass with SecureRandom implementations
• ✅ Added property-based tests using jqwik for comprehensive validation
• ✅ Performance benchmarks confirm acceptable performance characteristics
• ✅ Security contexts properly use cryptographically secure random generation

The migration maintains full backward compatibility while significantly improving the security posture of random number generation throughout OkHttp.

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