// Test case for issue #231
import org.checkerframework.checker.nullness.qual.EnsuresNonNull;
import org.checkerframework.checker.nullness.qual.Nullable;
class SelfAssignment {
void test(@Nullable String s) {
assertNonNull(s);
s = s.trim();
}
@EnsuresNonNull("#1")
void assertNonNull(final @Nullable Object o) {
if (o == null) {
throw new AssertionError();
}
}
}