Worked on the linq2db/linq2db repository to enhance developer experience and maintainability by improving documentation clarity around the IsNotNull method in PropertyMappingBuilder. Focused on C# and documentation best practices, the contribution updated the method summary to more accurately describe its behavior, specifying that it sets a column as NOT NULL and disallows any NULL values. This change did not alter runtime behavior but provided clearer guidance for both users and contributors, aiming to reduce future misinterpretations and support needs. The work demonstrated attention to detail in code refactoring and documentation, supporting long-term codebase maintainability and onboarding efficiency.