Compile this with -source 7:

public class RepeatedAnnotations {
    @SuppressWarnings("a") @SuppressWarnings("b") void m() {}
}

Output:

RepeatedAnnotations.java:3: error: repeated annotations are not supported in -source {0}
    @SuppressWarnings("a") @SuppressWarnings("b") void m() {}
                           ^
  (use -source 8 or higher to enable repeated annotations)

The "{0}" string is missing its actual value.