This example gives two incorrect "Dereferencing possible null pointer" hints.
1. The detector may be interpreting the assert condition incorrectly.
2. The detector should not assume the assert always runs.  (asserts only run if assertions are enabled.)

public class DerefNullHintBad {
  public static void run(Object value) {
    assert value == null || "".equals(value) : value.toString();
    if (value != null) {
      // ...
    }
  }
  public static void main(String[] ignore) {
    run(null);
    run("");
    System.err.println("nothing thrown");
  }
}

1. On the 'assert' line: "Dereferencing possible null pointer".  

But the assert condition explicitly allows null, so the value.toString() should only run if value is not null.  

2. On the 'if' line: "Unnecessary test for null - a NullPointerException would already be thrown"

This is wrong for two reasons: 
- same as #1 above, the assert does not throw NullPointerException, and 
- assertions only run if assertions are enabled.