Various simplifications to code and comments.

[copybara-service[bot]]

Various simplifications to code and comments.

This time, with a workaround for a breakage in code that uses a particular custom classloader.

Fixes https://github.com/google/guava/pull/6006

[BitoAgent]

Code Review Agent Run Status

• AI Based Review: Successful
• Static Analysis: Partially Successful - Failed to execute static code analysis using fb_infer

Code Review Overview

• Summary: This PR introduces several modifications to the CacheBuilder and LocalCache classes, focusing on code simplification and optimization. Changes include minor edits for clarity and consistency in comments and documentation, refactoring to enhance readability and maintainability, and updates to utilize more concise and efficient Java language features. The modifications also address potential issues related to the use of method references and lambdas in specific contexts, ensuring compatibility and preventing runtime errors. Overall, the PR aims to improve the codebase's quality without altering the existing functionality or performance characteristics.
• Code change type: Refactoring, Configuration Changes, Performance Improvement, Other
• Unit tests added: False
• Estimated effort to review (1-5, lower is better): 2. The changes are straightforward and localized to specific methods, but a careful review is necessary to ensure that the modifications do not introduce regressions or alter the intended functionality.

>>See detailed code suggestions<<
The Bito AI Code Review Agent successfully reviewed 5 files and discovered 13 issues. Please review these issues along with suggested fixes in the Changed Files.

High-level Feedback

• General feedback for improvement:

1. Ensure comprehensive testing to validate that the refactoring and optimizations do not alter the cache's expected behavior, especially in concurrent scenarios.
2. Consider adding unit tests for newly introduced utility methods or significant refactoring to existing methods to safeguard against future regressions.
3. Review the use of lambdas and method references in contexts that might affect class loading or initialization, particularly in sensitive environments like custom ClassLoaders or system classloaders. The PR addresses this concern with comments, but it's crucial to maintain awareness of such potential issues in future changes.