Developed a new filtering capability for the camunda/camunda-bpm-platform repository by implementing the taskDefinitionKeyNotIn parameter in the Task Query API, allowing clients to exclude tasks based on specific task definition keys. This work involved updating OpenAPI templates, modifying data transfer objects, and enhancing the query implementation to support more precise task retrieval. Comprehensive tests were added to ensure reliability and correctness. Utilizing Java, FreeMarker, and skills in API design and backend development, the update improves workflow management by reducing unnecessary data transfer and server load, particularly for clients handling large task datasets, and enhances the overall user experience.