This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
We only have good threads here (and if you believe that, you will believe anything )
HashMap is a library class; as people implied on that thread, a library class should be provided with all possible actions, As Joanne Neal (who is an asset to this website) said, it is easy to wrap HashMap to prohibit null keys (or also prohibit null values) but not to permit nulls if the enclosed class prohibits nulls.