I created a simple test project that uses @NotNull. I added a dependency on a library that defines it (a copy of the IDEA annotations.jar but with a different name). I added an import statement:
The program builds without error. However, the editor fails to find the library. It highlights "jetbrains" in red and says it can't resolve the symbol. Same for @NotNull.
I have observed this problem in IDEA CE 13.1.1, 13.0.2, and 12.1.
Oddly, the problem does not occur in 11.1.2.
Am I missing something, or is this a regression that has not been observed?