Worked on the googleapis/java-bigtable repository, delivering a focused refactor to improve error message formatting within the Preconditions logic. The approach involved replacing String.format usage with direct format strings and arguments, which enhanced message clarity and reduced the risk of runtime formatting issues. Throughout the process, the core mutation limit checking logic remained unchanged, ensuring no impact on existing business functionality. This work demonstrated disciplined Java development practices, with careful attention to error handling and maintainability. The changes contributed to more readable and reliable error messages, reflecting a methodical approach to API development and codebase quality within a Java environment.